PowerManagerService: call surfaceflinger blank and unblank through binder

Synchronize with SurfaceFlinger during screen off and on to ensure that
a black frame has been drawn on the display, and then trigger all early
suspend handlers on devices that have early suspend, as well as PowerHAL
operations.

Change-Id: I8a5ad5a84c9e80ce5bb8f7f0b09b064e2b9ad4ef