m8: Enable offload for PCM/AV streaming

 * Also cleanup useless audio policy entries

Change-Id: I1c2e8b4f86a8b16f807896bc3bfa96acd43e1c0a
overlay: route calls to mute mic through AudioManager

Change-Id: Ic92978f9647e510f9bcff6b1d8e9e3efbefdd010