audio: enable tunnel mode based on flags

- Enable tunnel mode playback based on flags defined
  in target board config file instead of checking
  target name.

(cherry picked from commit 55a727f33978d374ffbdf612dd4a8560c3bffe3f)
(cherry picked from commit bb7234c9bb0505f3d6df998f84b9a062b206e097)

Change-Id: I78c39b2653e7bae6a6eae8de36fbcacbeb1e6686