msm_fb: Fix the hang issues due to improper usage of vsync

For LCDC/DSI command/DTV interfaces, fix the various corner cases
of wait4vsync getting stuck due to TG turned off/wait4sync
count being reset to zero etc. Add timeout to waiting for vsync
to avoid hang issues when vsync interrupt is turned off.

Change-Id: I97322f3f1c6cc13b484cfa594d2fadcdec53d48a
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>

Conflicts:

	drivers/video/msm/mdp4_overlay_dsi_cmd.c
	drivers/video/msm/mdp4_overlay_dtv.c
	drivers/video/msm/mdp4_overlay_lcdc.c