msm: mdss: fix command mode static screen issue on mdp3

For command mode panels on mdp3 vsync expire tick starts
count down on vsync disable call from userspace. If commit
call comes without vsync enable there wont be corresponding
disable call. In this case the vsync tick doesn't start
count down and clocks will be left on even while device is
in static screen. Force start the dount down on commit if
the vsync is not enabled to make sure the clocks are turned
off properly.

Change-Id: I23479b4e119c189e6dc75b9d35683bf2195d7c22
Signed-off-by: Shivaraj Shetty <shivaraj@codeaurora.org>