drm/msm/mdp: Add capabilities to MDP planes (v2)

drm/msm/mdp: Add capabilities to MDP planes (v2)

MDP planes can be implemented using different type of HW pipes,
RGB/VIG/DMA pipes for MDP5 and RGB/VG/DMA pipes for MDP4. Each type
of pipe has different HW capabilities such as scaling, color space
conversion, decimation... Add a variable in plane data structure
to specify the difference of each plane which comes from mdp5_cfg data
and use it to differenciate the plane operation.
V1: Initial change
V2: Fix a typo in mdp4_kms.h

Signed-off-by: Jilai Wang <jilaiw@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>