msm: mdss: sync point factoring to allow async signaling

Refactor sync point implementation by using a commit thread to handle
all commits for better performance. By using commit thread we can also
allow unblock user space to program new frames while the update is still
in progress. Allow for async notifications to be done when frames are
flushed (new frame can be programmed) and frame is done (new frame can
be displayed).

Change-Id: I0952f3f0ea9273a92c74fa42cd3ca9c6f9d042f3
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>

Conflicts:
	drivers/video/msm/mdss/mdss_fb.h