msm: mdss: add support for dedicated rotator control

In some MDP revisions, there is a control path that supports
only rotator operations whereas in other MDSS variants,
the same path can support both WFD and rotator. This change
takes care of this. Also, makes changes to support dedicated
WFD block.

Change-Id: Ife6ebd39a3f6a42501baeb2a8d4c6c8e1a9db39a
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>