hwc: Do not unset pipe for MDP3 targets

Their is no borderfill for MDP3 targets, so DMA pipe should be
attached always, except suspend. In case of no app layers,
we unset all pipes. We have to avoid this for MDP3 targets.

Change-Id: Ibae2c97af18a2c92157d0d5f48b46864e58fdd35
1 file changed