libhardware: Add fix for offload playback.

-Offload mode requires frame size to be unity.
-Tunnel encode changes results in a invalid frame size being
 returned to audio flinger.
-Add 24 bit PCM format as exception to linear pcm.

Change-Id: If32c703b4c3543c2a7df2a75528cc5f99e42c967
Merge remote-tracking branch 'du/du44' into du44