HFP: recover BT_SCO and set audio parameters while audio server restarted

While audio sever died and restarted, need reset BT_SCO and audio parameters
to recover audio path on BT_SCO device. Register audio server state callback
in HeadsetService and restore BT_SCO, audio parameters and a2dpSuspended flag
in onAudioStateUpcallback.

Change-Id: If5c91e91e3b0934728b1c2b71d15a7862081bf74
CRs-fixed: 2527071
2 files changed