hal: Fix a2dp mute issue on voice activation/music concurrency

- A2dp streaming is muted immediately after
  voice recognition is terminated on music + voice
  recognition concurrency
- Music is paused as a part of voice activation.
  However compress session close happens only after
  pause timeout(10secs),if resume request comes before
  pause timeout as a2dp session is already active from HAL
  IPC start will not be called which resulting audio mute
- Call a2dp start to BT IPC library post suspend state
  based on number of active session count

Change-Id: Ic078923694c63e496dd5c8d58323fb69ee5492da