msm: mdss: sync point support

MSMFB_BUFFER_SYNC ioctl is added for hwc to pass
in buffer fence, driver creates release fence and
return to hwc.

Before display update, driver waits for the fence to
be signaled. Signal the release fence after update is done.

Change-Id: I3d8cd5e8df1f0415832507d19cf629f4c0432164
Signed-off-by: Ken Zhang <kenz@codeaurora.org>
4 files changed