fbdev: msm: use sync_file interface for fence

use sync_file interface for fence handling.

mdss_sync.h, mdss_sync.c are derived from sde_rotator_sync.h
sde_rotator_sync.c from commit 281fc6b6 ("msm: sde: add support
for sync file to sde rotator").

Change-Id: I8ef479bb096300a4ea055d4dd226b9d092db1f84
Signed-off-by: Sachin Bhayare <sachin.bhayare@codeaurora.org>