hwc: Release non VIG pipes during padding round and HDMI configure

1. Fall back to video only composition instead of full GPU composition
   to release all pipes assigned to RGB layers for primary display
   during external configuration and padding round. Do this only for
   the target which has total number of pipes >= 8.
2. This resolves blinks when HDMI is connected during secure video
   playback usecase.

Change-Id: I6cf3a20c3eb3c2b82ad6c70eba84292cf59ecf26
1 file changed