SystemUI: Ensure that the Clock is actually enabled in IconMerger

to device if we need to calculate

Change-Id: If12b0e26b32f044f1a82cf8b539283194d1d0b4c
Keyguard: Enable quick unlock (1/2)

old way does not work anymore exactly like before. So adapt the idea to new LP code

Thankd DVTonder for the basic idea prior LP

PS:
- do PIN view correctly
- Hide OK button if quick unlock is enabled on PIN view

Change-Id: I86660afafb8648d36d6c135343c88afcfc5173fc

Conflicts:
	core/java/android/provider/Settings.java