Add support for USB audio docks.

Associate Android device type DEVICE_OUT_DGTL_DOCK_HEADSET with a UAC
peripheral with terminal type 0x602 to allow specific audio policy for
docking stations with speaker and USB connectivity.

Bug: 197584191
Test: make
Change-Id: I090e86b2e3e7666f3978ef904a922b040bcb44e4