msm: mdp3: implement overlay prepare ioctl for mdp3 driver

Implement overlay prepare ioctl call for mdp3 display driver. This will
allow a full frame with multiple overlays to be configured at once and
perform frame level checks before being pushed to display. This function
guarantees that if the call is successful, the frame can be displayed
successfully on the screen when display commit is called.

Change-Id: I761f48f81512fbe538565c4622d9299857350da1
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>