msm_mdp: Update header for 4 layer support

Bug: 7626586
Change-Id: I37730470dc09b7a9d6336b1603f87efd98f45e97
Signed-off-by: Iliyan Malchev <malchev@google.com>
Merge tag 'android-4.2.2_r1' into jellybean

Android 4.2.2 release 1

Conflicts:
	libc/kernel/common/linux/msm_mdp.h