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
Merge "Power Menu: Update the Expanded Desktop drawable" into cm-10.1
Merge branch 'cm-10.1' of git://github.com/CyanogenMod/android_frameworks_base into cm-10.1-n7