telephony: Disable handling audio direction changes on IMS calls.

I6f84e2b90e572c0973dcf04ce1e0c8e5e3524467 (AOSP) introduces
handling of changes of the audio direction between major call state
changes.

This breaks ringback tone when establishing IMS calls
on other devices, so make it configurable.

Change-Id: I29331b7e8ea8f048f4567518b2173c6d7e503a6c