msm: display: Buffer sync point support

Add MSMFB_BUFFER_SYNC ioctl for the communication of
the acquired and released fence fd between kernel and hwc.

Wait for acquired fence before pan display.
Release the previous released fence after pan display

Change-Id: I6534aed574a025d948581e70465f06a86b46c868
Signed-off-by: Ken Zhang <kenz@codeaurora.org>

Conflicts:

	drivers/video/msm/msm_fb.c