Keyguard: fix transparent lockscreen

Change-Id: Icdd8bc5605dd352b03772880764b5ca39d74a3e5
Signed-off-by: Dirk Rettschlag <dirk.rettschlag@gmail.com>
Merge "Keyguard: fix transparent lockscreen" into kitkat
Merge commit 'ee0bfcf6d26343189a82c4f1344f7c5fd36d7343' into kitkat