AudioTrack: fix write retries for compressed audio

When the amount of frames that can be written to the buffer
is less than requested, AudioTrack::processAudioBuffer() estimates
the time needed to free the missing amount of frames and asks the
callback thread to sleep.
This behavior is not possible for compressed audio and should not
be enabled for offloaded tracks.

Change-Id: I5b657283cfba06254c9ac0ea9b447467cce7eb61