Keyguard: Correctly set the visibility

What a day. Small derp due that the keyguard does not gets every time reinflated
we need to ensure that the visibilities are set correctly if the user changed the
configuration.

Sorry for 2 fix commits today

Change-Id: I2c7f4501c3ef589e515afe6d5ca07c1286bed5f3
Keyguard: Fix another derp and check against null

good night

Change-Id: Ia31af94024fa9884153015be807bfc89dc5502f7