Decouple critical policy power update from SCREEN_ON broadcast

This attempts to fix a bug where ordered broadcasts like
ACTION_SCREEN_ON are substantially delayed by misbehaving
receivers.  Instead, we immediately send the state to mPolicy
so that it can wake/sleep the device without delay.

Fixes bug 14313639

Change-Id: I21a191f90e0a19f1ee75c160ecc4e63e8def709e