audioflinger: Fix to set correct volume in Tunnel playback

http://review.cyanogenmod.org/#/c/32212/
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- After a pause and resume, tunnel playback volume is always
  set to maximum irrespective of the volume value before pause.
- The cause for this is, the stream volume is not used to set
  the volume in directaudiotrack.
- Fix is to use the stream volume to set volume during tunnel
  playback.

Change-Id: I59cda146ed88bd5c4186aeb9ae5d165f4a27493f
CRs-fixed: 452285
Signed-off-by: DHO <DHO@dho.im>