function hotkeys don't match key labels on Sony U101

While the expected hotkey functionality is present (brightness, volume, mute),
the behavior of the function keys does not match their labels. I've created a
table of keys that either have labels or actions (or both).

Key | Label | Actual Behavior
---------------------------------------------
Fn+F2 | None | Toggle Mute
Fn+F3 | Mute | Volume--
Fn+F4 | Adjust Volume | Volume++
Fn+F5 | Adjust Brightness | Brightness--
Fn+F6 | None | Brightness++
Fn+F7 | Toggle Ext. Monitor | Nothing
Fn+F12| Suspend to Disk | Nothing
Zoom/Rotate | Zoom/Rotate | Nothing
ThumbPhrase | ThumbPhrase | Nothing
Standby | Standby | Nothing
Power Save | Power Save | Nothing

Note: /var/log/acpid properly reports each keypress as an event for any Fn+key
combination (sony/hotkey SPIC 00000001 000000##)

IIRC, the original sony design was to have the function keys toggle an OSD
slider [========....] that could be manipulated with the arrow keys, hence the
layout of the special keys. Lacking this isn't fatal, but it is harder to figure
out which key should do what without a visual guide.

== Missing functionality:

The sleep button should probably be bound to hibernate/sleep (depending on which
is enabled), but neither suspend-to-disk nor standby keys do anything. Event codes:

* Standby: (same as Fn+Escape) sony/hotkey SPIC 00000001 0000000b
* Fn+F12 (Suspend-to-Disk) sony/hotkey SPIC 00000001 00000017