Wily update to v4.2.6 stable release

SRU Justification

    Impact:
       The upstream process for stable tree updates is quite similar
       in scope to the Ubuntu SRU process, e.g., each patch has to
       demonstrably fix a bug, and each patch is vetted by upstream
       by originating either directly from Linus' tree or in a minimally
       backported form of that patch. The v4.2.6 upstream stable
       patch set is now available. It should be included in the Ubuntu
       kernel as well.

       git://git.kernel.org/

    TEST CASE: TBD

       The following patches are in the v4.2.6 stable release:
mac80211: Fix hwflags debugfs file format
ath9k: declare required extra tx headroom
mmc: core: Fix init_card in 52Mhz
iwlwifi: dvm: fix D3 firmware PN programming
iwlwifi: fix firmware filename for 3160
rtlwifi: rtl8821ae: Fix system lockups on boot
iwlwifi: mvm: clear csa countdown when AP is stopped
iwlwifi: mvm: fix D3 CCMP TX PN assignment
iwlwifi: mvm: fix D3 firmware PN programming
iwlwifi: mvm: init card correctly on ctkill exit check
iwlwifi: mvm: flush fw_dump_wk when mvm fails to start
iommu/vt-d: fix range computation when making room for large pages
iommu/amd: Fix BUG when faulting a PROT_NONE VMA
iommu/amd: Don't clear DTE flags when modifying it
powerpc/rtas: Validate rtas.entry before calling enter_rtas()
drm: fix mutex leak in drm_dp_get_mst_branch_device
drm: Correct arguments to list_tail_add in create blob ioctl
drm: crtc: integer overflow in drm_property_create_blob()
m88ds3103: use own reg update_bits() implementation
si2157: Bounds check firmware
si2168: Bounds check firmware
rtl28xxu: fix control message flaws
KVM: arm: use GIC support unconditionally
ALSA: hdac: Explicitly add io.h
ALSA: hda - Fix inverted internal mic on Lenovo G50-80
ALSA: hda - Fix deadlock at error in building PCM
ASoC: Add info callback for SX_TLV controls
ASoC: wm8904: Correct number of EQ registers
x86/efi: Fix multiple GOP device support
x86/ioapic: Prevent NULL pointer dereference in setup_ioapic_dest()
mm: make sendfile(2) killable
fault-inject: fix inverted interval/probability values in printk
tracing: Have stack tracer force RCU to be watching
bus: arm-ccn: Fix irq affinity setting on CPU migration
drm/radeon/dpm: don't add pwm attributes if DPM is disabled
drm/amdgpu: add missing dpm check for KV dpm late init
drm/i915: Flush pipecontrol post-sync writes
drm/i915: Restore lost DPLL register write on gen2-4
drm/i915: Deny wrapping an userptr into a framebuffer
drm/radeon: don't try to recreate sysfs entries on resume
drm/amdgpu: don't try to recreate sysfs entries on resume
drm/radeon: fix dpms when driver backlight control is disabled
drm/radeon: move bl encoder assignment into bl init
iio: mxs-lradc: Fix temperature offset
iio: st_accel: fix interrupt handling on LIS3LV02
iio: accel: sca3000: memory corruption in sca3000_read_first_n_hw_rb()
rbd: require stable pages if message data CRCs are enabled
rbd: don't leak parent_spec in rbd_dev_probe_parent()
rbd: prevent kernel stack blow up on rbd map
ARM: EXYNOS: Fix double of_node_put() when parsing child power domains
ARM: orion: Fix DSA platform device after mvmdio conversion
ARM: mvebu: correct a385-db-ap compatible string
ARM: dts: berlin: change BG2Q's USB PHY compatible
ARM: dts: Fix audio card detection on Peach boards
ARM: dts: imx7d: Fix UART2 base address
ARM: dts: am57xx-beagle-x15: set VDD_SD to always-on
ARM: ux500: modify initial levelshifter status
ARM: OMAP1: fix incorrect INT_DMA_LCD
ARM: 8445/1: fix vdsomunge not to depend on glibc specific byteswap.h
ARM: 8449/1: fix bug in vdsomunge swab32 macro
Revert "ARM64: unwind: Fix PC calculation"
arm64: kernel: fix tcr_el1.t0sz restore on systems with extended idmap
block: don't release bdi while request_queue has live references
dm btree remove: fix a bug when rebalancing nodes after removal
dm cache: the CLEAN_SHUTDOWN flag was not being set
dm btree: fix leak of bufio-backed block in btree_split_beneath error path
nvme: fix 32-bit build warning
Revert "serial: 8250_dma: don't bother DMA with small transfers"
USB: qcserial: add Sierra Wireless MC74xx/EM74xx
i2c: mv64xxx: really allow I2C offloading
clkdev: fix clk_add_alias() with a NULL alias device name
fbcon: initialize blink interval before calling fb_set_par
xhci: handle no ping response error properly
xhci: Add spurious wakeup quirk for LynxPoint-LP controllers
xen-blkfront: check for null drvdata in blkback_changed (XenbusStateClosing)
module: Fix locking in symbol_put_addr()
PCI: Prevent out of bounds access in numa_node override
ovl: free stack of paths in ovl_fill_super
ovl: free lower_mnt array in ovl_put_super
ovl: use O_LARGEFILE in ovl_copy_up()
ovl: fix dentry reference leak
ovl: fix open in stacked overlay
Input: alps - only the Dell Latitude D420/430/620/630 have separate stick button bits
crypto: api - Only abort operations on fatal signal
md/raid1: submit_bio_wait() returns 0 on success
md/raid10: submit_bio_wait() returns 0 on success
md/raid5: fix locking in handle_stripe_clean_event()
Revert "md: allow a partially recovered device to be hot-added to an array."
EDAC, sb_edac: Fix TAD presence check for sbridge_mci_bind_devs()
irqchip/tegra: Propagate IRQ type setting to parent
mvsas: Fix NULL pointer dereference in mvs_slot_task_free
netfilter: ipset: Fix sleeping memory allocation in atomic context
btrfs: fix possible leak in btrfs_ioctl_balance()
kvm: irqchip: fix memory leak
thermal: exynos: Fix register read in TMU
um: Fix kernel mode fault condition
blk-mq: fix use-after-free in blk_mq_free_tag_set()
IB/cm: Fix rb-tree duplicate free and use-after-free
sched/deadline: Fix migration of SCHED_DEADLINE tasks
cpufreq: intel_pstate: Fix divide by zero on Knights Landing (KNL)
arm64: compat: fix stxr failure case in SWP emulation
NVMe: Fix memory leak on retried commands
drm/vmwgfx: Fix up user_dmabuf refcounting
thp: use is_zero_pfn() only after pte_present() check
pinctrl: baytrail: Serialize all register access
pinctrl: baytrail: Use raw_spinlock for locking
xen: fix backport of previous kexec patch
Linux 4.2.6

The following patches from 4.2.6 were already present in the wily kernel:
drm/nouveau/gem: return only valid domain when there's only one
iwlwifi: pci: add a few more PCI subvendor IDs for the 7265 series