hal: Add suport for dedicated VoIP devices

 * Some devices out there have dedicated paths for VoIP, add support
   for these by setting the system property.

Change-Id: I59cd97e78427f811559081a04151c9a2eccf452f
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_hardware_qcom_audio-caf into cm-11.0