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>