Power Menu: Update the Expanded Desktop drawable

Also add a proper "off" state.

Patch Set 2-4: Add to symbols.xml
Patch Set 5: Remove the useless extra sw600dp-xhdpi drawable

Change-Id: I111982a4985bba19353dd4f3872e5b21e73dd5f9

Conflicts:
	core/res/res/drawable-sw600dp-xhdpi/ic_lock_expanded_desktop.png
	core/res/res/values/symbols.xml

Signed-off-by: Paul Beeler <sparksco@gmail.com>