audio: changes for audio device API 2.0.

Removed implementations of obsolete function get_supported_devices()

Audio HAL wrapper provides conversion between new and old device enums.
It exposes a rev 2.0 audio device API to the audio framework and allow
legacy implementation to use old device enums.

TODO: make sure that Qualcomm proprietary device IDs are defined properly.

Change-Id: I6779d6c9bccb531d70d84136cdc8d56208b5c934