linaro-hwpack-install: add FORCE_OPTIONS to apt update

linaro-hwpack-install stops and asks for user interaction when trying to
update APT cache from unsigned repositories. Could you please allow
FORCE_OPTIONS to be present when APT tries to update its cache?

Find attached a proposed patch to fix the issue:

--- linaro-image-tools-2012.03.orig/linaro-hwpack-install
+++ linaro-image-tools-2012.03/linaro-hwpack-install
@@ -181,17 +181,17 @@ fi
 echo "deb file:${HWPACK_DIR}/pkgs ./" > "$SOURCES_LIST_FILE"
 cat /etc/apt/sources.list >> "$SOURCES_LIST_FILE"

-echo "Updating apt package lists ..."
-$sudo apt-get -o "$APT_GET_OPTIONS" update -q
-
-echo -n "Installing packages ..."
-
 if [ "$FORCE_YES" == "yes" ]; then
  FORCE_OPTIONS="--yes --force-yes"
 else
  FORCE_OPTIONS=""
 fi

+echo "Updating apt package lists ..."
+$sudo apt-get $FORCE_OPTIONS -o "$APT_GET_OPTIONS" update -q
+
+echo -n "Installing packages ..."
+
 # "newer" hwpacks contain a dependency package whose Depends is the
 # same as the packages config setting from the file the hwpack was
 # build from. But if we just installed that, a newer version of a