hal: Correctly set backend to best available parameters

* For the case where CALL/IN_COMMUNICATION, new_bit_width and
  new_sample_rate were unconditionally reset to 0, resulting
  in a sample rate/bit width change always occurring.
  Don't do this for CALL/IN_COMMUNICATION as the original
  logic intended.

Change-Id: Ib647cec084f4af9a044f90935dd57257bba0ec06