hal : fix a2dp-sco concurrency issue with combo use case.

A2dp playback is not working fine if sco path setup
is done post bt_sco off.

Add speaker-safe and a2dp combo device for force restart.
Reroute existing combo use cases from speaker-btsco to speaker-a2dp
if any of use case is routed from speaker-btsco to speaker-a2dp.

Change-Id: I694145facdb0ed6d642c356c620e43297bbaaff1