gralloc: Use compile time flag for mdss.

The gralloc allocation can happen from processes other than
surfaceflinger in which case we cannot open the framebuffer
device to get the mdp version. Use the MDSS_TARGET flag to
differentiate.

Change-Id: I69bc9ff6004b382a2836274a32fbbd3b2e67dea2
Fix media playout on 8974

Yeah, we need the venus color format on recent platforms, and
I can't reproduce the clean_headers conflict...

Change-Id: I47fcaea999cce01c29681c7acdf456a12785a34e
hwc: Silence some logging

Change-Id: I3eb64b2557ce1d533486c89ac2bd648522bf74ca