HWC2: Check all displays for client composition

SurfaceFlinger currently only checks whether the primary display
performed client composition when considering whether to propagate
backpressure back to apps. This change expands that check to all
displays so that if an external or virtual display is using client
composition it disables backpressure propagation as well.

Bug: 30022738
Change-Id: I7f7d4e0a1ea7d27ef1f280e2b4ebd5e5bd3bd911