audio: Define Proxy device

- Added Proxy device changes

Change-Id: I47921d696171de40bcfc30ebf99d4cafa0d4d4a3
(cherry picked from commit a8b7ed78ec088bc6924854661bacde51d7194ab3)
(cherry picked from commit cff61cfd964a1150919d9bfa7ec0ebfe35d5f247)
(cherry picked from commit bf8f7a2a574cb2e6aafae3efa6e4ee163ef65cf7)