Re-Add USB Dock audio output devices to policy

Relies on http://review.cyanogenmod.org/#/c/30482/

Patch set 3: Remove draft

Change-Id: I0e4b9a76158cf6f7478f28c3540e9513b2e9c2bf
d2: don't hide focus modes

taken from: http://review.cyanogenmod.org/#/c/28717/
Change-Id: Id3b972891127eee523cb1b71ca6576b01341fd78