alsa_sound: port fixes for USB audio and misc issues

Issues:
 Music audio lost on headset when we end call and call volume in silent
 mode.
  Fix:Ensure that proper suspend and resume happens while we get a2dp
      state as playing while in a call
  CRs-Fixed: 482213

 Some USB headsets start at 0 volume because of this even
 if the Media Player volume is maximum cannot hear any audio.
  Fix : Initialize device volume before starting the playback.
  CRs-Fixed: 478906

Change-Id: I29275497982d932c32f7bc6e12078090f6d99bf7