Terminate PBAP service cleanly during BT off

PBAP service runs in a loop of 10 trials to create the RFCOMM listener
thread; this loop is not getting interrupted during BT off, due to which
we end up delaying PBAP stop by 3 seconds (10 * 300ms). The fix is to
check for BT state after RFCOMM listener failure and break out of the
loop if BT is being turned off.
bug 7134544

Change-Id: I35db2221be30980bec973253cdd888e0ce8cc36b