audio: Fixed streamType for non-media streams

- When application passes attributes with non-media
  usage, it is wrongly converted to AUDIO_STREAM_MUSIC
  in AudioTrack and sent to AudioPolicyManager.
  This is causing wrong output to be selected by
  AudioPolicyManager. testTwoChannelCapturing is failed
  due to this reason

- Fix is to set mStreamType to be DEFAULT when
  attributes are passed by the client to AudioTrack

CRs-Fixed: 813683
Change-Id: Ibdb4859f9eb838b7b930e2509de1d98d62e1599d