Call requestFocus and ensure that screenOn is set.

When maybeCreateKeyguardLocked was called from methods other than
show(), the requestFocus() call on the new KeyguardHostView was
never made.

At boot time the screen on notification was not propagated to
KeyguardViewManager because the showListener callback was null.
This passes on the notification but does not make the callback
if it is null.

Bug: 7299119 fixed.
Change-Id: Iaf058954473dc63fe4864ab1f435db4463b1110e