HFP: Set audio handle for active device during incoming call

* Set audio handle for active device during incoming call
* Change debug level logging to warning level when SCO is not allowed to
  open or when RING command is not allowed to be sent

Bug: 77949569
Test: connect with HFP devices and receive incoming call
Change-Id: Ibc2caf740f94817ae725786e35e8592390167ce2