t0lte: disable voicecall route on init & leaving incall state

Change-Id: Ida0a5d2066fe45a1f929188dc67b786d43a02a9b
t0lte: audio: don't disable back mic upon voice call end

Back or Secondary Microphone (Sub Mic) is turned on and off
using noise_suppression parameter from adev_set_parameters
and hence it is not required to disable the back mic explicitly
in voicecall_default_disable.

Change-Id: Ic89d9f978353f3a067031b8e45dd9333d0738aad
Merge changes Ic89d9f97,Ida0a5d20 into android-4.4

* changes:
  t0lte: audio: don't disable back mic upon voice call end
  t0lte: disable voicecall route on init & leaving incall state