Reset the FrameNumber for dropped frame in async mode

In Async, reset the framenumber of frames dropped by the BufferQueue.
This allows the client to dequeue and use this frame before the other
queued frames which may be with the MDP.

CRs-fixed: 448606
Change-Id: Icaabf77b55a7275dc98ba1fdfba89508feb92145
Revert "SurfaceFlinger: Change to support framebuffer flip for 2D blitters"

This reverts commit f442ef1dfc17ca56b88c68c318599942f94e1d68.