msm: mdss: Implement basic assertive display functionality

Provides starting control logic and register access for initialization,
configuration, and input to assertive display (AD) feature. AD allows for
several modes of operation that can be used to increase display visibility
under various viewing conditions.

Change-Id: I5db510e36c6b9394626e8efe8160d792c8bdda01
Signed-off-by: Carl Vanderlip <carlv@codeaurora.org>