msm: mdss: wait for ping pong during unblank kickoff

During panel unblank a kickoff is done to turn on the panel so that the
first update is not delayed. However since buffer sync and display
commit is not called on this, need to make sure that the update finishes
completely including the workqueue that signals the fences. Signaling
the sync fence can potentially cause timeline to be ahead and end up
signaling the acquire fences early leading to source tearing on command
mode panels.

Change-Id: I56edf8355e1c635c3da24f20405c3ae4fe31cf2e
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>
msm: mdss: add wait4pingpong in stop func

stop function may shut down mdp clocks while display thread kicked off
a frame and is waiting for pingpong done. Adding this wait to avoid
the race condition.

Change-Id: I7f081dd952cf2f7218e5471e6f735b8e09ba75fa
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>
Signed-off-by: Naseer Ahmed <naseer@codeaurora.org>