msm_fb: Make Vsync IOCTL during disable sequence as NO WAIT

Change to make the vsync IOCTL no wait during the disable sequence.
This is to increase the performance. Handle the synchronization of
vsync interrupt using state variables in drivers from now.

Change-Id: Ia5ec14493f233a95f21d01ea627200a6c278239f
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>