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/values/symbols.xml