audiopolicy: Update voice concurrency support for 8916

    - Previous versions of 3rd party voip applications used
      mode MODE_IN_CALL instead of MODE_IN_COMMUNICATION.
    - To avoid voice concurrency code getting executed in
      such cases the check for in_call was added in audiopolicy
      to determine if we are in actual voice call.
    - This change is not required now as all the 3rd party voip
      applications set the expected mode, MODE_IN_COMMUNICATION.

    CRs-Fixed: 1113432

Change-Id: I44c13e177d7fda51a43481ce560d399a4633c38a