AudioDevice class is only used by Virtualizer so
far so it does not need to be public yet.
Also removed redundant DEVICE_ prefix to device
types.
Bug: 17059703.
Change-Id: I5c93f66487b35de24f28641141f8e7de9e85c6c2
Unhide the new method to query the Virtualizer effect implementation
about its capabilities in terms of input, device support, and
virtual speaker angles.
Change-Id: I4478f7837efe8c9d52978244a3402c7f8590e585
