drm/msm/sde: support posted frame trigger for cmd mode

Support posted frame trigger for command mode
panel with queue depth 1. It allows panel vsync time
for frame transfer duration and reduces the MDP clock
and BW requirement. The change also support debugfs
entry support to select the cmd mode frame done wait
between serialize trigger, posted trigger and default
behavior.

Change-Id: I84134a6458665c40e94aa29805e528caa2d91a93
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>
Signed-off-by: Bruce Hoo <bingchua@codeaurora.org>
Signed-off-by: Ray Zhang <rayz@codeaurora.org>