drm/msm/mdp5: Misc cursor plane bits

These are various changes added in preparation for cursor planes:

- Add a pipe_cursor block for 8x96 in mdp5_cfg.
- Add a new pipe CAP called MDP_PIPE_CAP_CURSOR. Use this to ensure we
  assign a cursor SSPP for a drm_plane with type DRM_PLANE_TYPE_CURSOR.
- Update mdp5_ctl_blend_mask/ext_blend_mask funcs to incorporate cursor
  SSPPs.
- In mdp5_ctl_blend, iterate through MAX_STAGES instead of stage_cnt,
  we need to do this because we can now have empty stages in between.
- In mdp5_crtc_atomic_check, make sure that the cursor plane has the
  highest zorder, and stage the cursor plane to the maximum stage #
  present on the HW.
- Create drm_crtc_funcs that doesn't try to implement cursors using the
  older LM cursor HW.
- Pass drm_plane_type in mdp5_plane_init instead of a bool telling
  whether plane is primary or not.

Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>