msm: mdss: wake up cpu before vsync for command interface

Waking up cpu before vsync time can reduce isr latency to avoid frame
drops due to power collapse. This change adds the feature to command
interface based on the same feature that was already implemented in
video interface.

CRs-fixed: 486116
Change-Id: Ia29df017a5d28f580f22c9a8fd62e22bcd78fa52
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>