audio: add support for incall music

- Define AUDIO_STREAM_INCALL_MUSIC to support
  incall music

Change-Id: I11319f3120a4243803ec2f8b8fc024f696a8a7da
fs_mgr: wait for device-mapper control file

When setting up a verified mountpoint, wait for the /dev/device-mapper
control node to appear.

Change-Id: I50bb64213fe08ba7b552055045d35915903fb532