media: Require property to be set to use QC AV enhancements

 * Because of the wild divergence between branches and the fragility
   of this interface, we will disable it by default even if the
   library is in place. After thorough testing for a device it
   can then be enabled. At this point, these enhancements bring
   little value except on the very latest hardware.

Change-Id: I99147a466bfbb020d05ffbb6c2773414f2439755