hwc: Alpha downscale on MDP4 is not a hard condition.

Alpha downscaling check should be applied to the full and partial
mdp comp checks rather than as a hard-feature check.

This means we could still have a video going through MDP comp and
the volume bar (lets say) failing the Alpha downscale check.

Change-Id: I6a47057e826668f7f19e20b6d0a548fffa349de2
1 file changed