ActiveDisplay: Remove unnecessary IPowerManager getter for screen state

This lookup method was incredibly slow and was causing some performance issues.
 Lets replace it with a boolean set by the broadcast receiver that already
handles some screen state behaviors.

Change-Id: I36cdb4122e4d3ec49d860e5a7b2af84516d69b21

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/policy/activedisplay/ActiveDisplayView.java