msm: display: make pan display as a non-blocking call

Schedule a workqueue, do the current job in the workqueue handler.
Block the second entry if the first one has not finished

Change-Id: I9466c7795bd9d6765f468bf30f4021802d904c36
Signed-off-by: Ken Zhang <kenz@codeaurora.org>

Conflicts:

	drivers/video/msm/msm_fb.c

Signed-off-by: Naseer Ahmed <naseer@codeaurora.org>

Conflicts:

	drivers/video/msm/msm_fb.c