drm/msm: add plane support

Enable using VG1 and VG2 for planes.  Currently YUV/CSC or scaling is
not enabled, but ARGB and xRGB blending is.

Signed-off-by: Rob Clark <robdclark@gmail.com>
Acked-by: David Brown <davidb@codeaurora.org>

diff --cc drivers/gpu/drm/msm/mdp4/mdp4_crtc.c
Simple merge

diff --cc drivers/gpu/drm/msm/mdp4/mdp4_format.c
Simple merge

diff --cc drivers/gpu/drm/msm/mdp4/mdp4_kms.c
Simple merge

diff --cc drivers/gpu/drm/msm/mdp4/mdp4_kms.h
Simple merge

diff --cc drivers/gpu/drm/msm/mdp4/mdp4_plane.c
Simple merge

diff --cc drivers/gpu/drm/msm/msm_drv.h
Simple merge