drm/msm/sde: assign ctls based on capability requirements

Need to assign control path blocks based on matching use case
requirements to hardware block capabilities. Prefer to assign
lower capability blocks first so we are still able to serve
split display clients when they arrive.

Change-Id: I415da3c1aed8d7fa6a919eba1e730aa7c8e3751a
Signed-off-by: Lloyd Atkinson <latkinso@codeaurora.org>