msm: display: add sync point support in overlay commit

Wait for fence signaled before commit, signal previous
fence after commit done. Same as pan display

Signed-off-by: Ken Zhang <kenz@codeaurora.org>
Signed-off-by: Naseer Ahmed <naseer@codeaurora.org>

Conflicts:

	drivers/video/msm/mdp4_overlay.c
	drivers/video/msm/msm_fb.c