SurfaceFlinger: Change to support client target flip

- Add support to flip framebuffer target if
  HWC2 implementation requests for it.

b/38114488
b/68271386
CRs-Fixed: 2057401
Change-Id: I91422ef60a139cbaf491db219b216cd1252e7e63
Signed-off-by: Madhuri Athota <mathota@codeaurora.org>