msm_fb: display: no wait for vsync after suspend

There has possibility that overlay_unset() is called after
suspend had been done. In this case no wait_for_vsync is needed
for pulling mode interface (lcdc and dsi video mode) since
timing generator was turned off and hence no vsync interrupt
will be delivered. This will cause thread to hang up.

Signed-off-by: kuogee Hsieh <khsieh@codeaurora.org>