msm: mdss: add YUV smart blit support

Enable smart blit for full screen Video and UI layers,
swap Z-order of video and UI layer when destination ROI of both the
layers are same and enable inverse alpha blending between the layers.
Add sysfs node support to disable YUV blit optimization.

Change-Id: I5cb34f113ba694545c8239004ff067578f10df2b
Signed-off-by: Ramakant Singh <ramaka@codeaurora.org>