msm: mdp: Update sync pt. behaviour

Add a retire fence and clean up the existing release fence
implementation

Signed-off-by: Naseer Ahmed <naseer@codeaurora.org>
Change-Id: Iecf7e95d0786ac43aa6a12d70442936600c0249a
Signed-off-by: LeJay <LeJayEmail@gmail.com>

Conflicts:
	drivers/video/msm/msm_fb.c
msm: display: plane alpha support

Clean up the blending rule to follow blend_op set from hwc.
Use modulate alpha for plane alpha when it is not 0xff.
Keep backward compatibility if blend_op is not set.

Change-Id: I02fd3c3c7b5ace2e6eec22b2db0284161404a0fc
Signed-off-by: Ken Zhang <kenz@codeaurora.org>