drm/msm: Initial version post processing header

Define the interface for driver clients to program the post processing
blocks of SDE. DRM driver clients will query the supported feature info by
querying the properties of planes/crtc. Feature info will provide the
major number info for a feature which will let the driver clients to
program the post processing blocks.

Change-Id: I5a33fe089288b576b2b51bc44f13081013308c4e
Signed-off-by: Gopikrishnaiah Anandan <agopik@codeaurora.org>