stagefright: Handle offload fallback for 24-bit tracks

 * We need to carefully handle fallback in the 24-bit lossless
   sources for outputs such as A2DP, which cannot use PCM
   offload.
 * Clean up the code while in here as well.

Change-Id: I398d964a3c5b18f58fcc79376bc29222e796badc
Revert "appop: protect mediaserver with OP_RECORD_AUDIO op check."

This reverts commit 688b6b46db58bceb8fa0e5b3a14ea192153c0fd3.

Change-Id: I8b1feb4eb22257024ef4426988be7d5f084df9db