msm_fb: display: skip one vsync event after enabling mdp and vsync clk

Both mdp and mdp_vsync clks are disabled for command mode panel when
no new frames are being played. When they are re-enabled if new
requests come in, the first vsync event which is signaled by read
pointer interrupt arrives in a random time due to the sync between mdp
and panel, so skip it to maintain correct vsync timing.

Change-Id: I683b765e4a16d3d152b9270f5982234b94921f1e
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>
msm_fb: display: wake up system before vsync for cmd panel

Add this feature for cmd mode panel. The feature is to avoid frame
drops due to power collapse and it is already present for other
display interfaces.

Change-Id: Ic68f41cd59931294b592577475ed7480459f2cf8
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>