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
t0lte: properly set routing and standby after call

Disabling the voice call route using voicecall_default_disable is not
sufficient since there are additional routes which are used during a
voice call, which have to be properly disabled. Also, set the input
device to standy which prevents the mic from not working for the
first time after a voice call.

This could also serve a potential fix for battery drain issues after
voice call.

Change-Id: Ie557b00e3979b588ea8e1b6b719de451f158935c