msm: mdss: Move evaluation of Assertive Display state machine

Move the Assertive Display (AD) state machine to a location where it is
evaluated once per frame instead of current location where it is evaluated
once per frame per DSPP. This change is beneficial in the support of dual
pipe cases of AD.

Change-Id: I2c6e17b92505c4cce13caeca0568f85d3c3337fa
Signed-off-by: Carl Vanderlip <carlv@codeaurora.org>