audio policy config: add USB_HEADSET device

Add definitions and routes for USB_HEADSET device
in default audio policy configuration for USB HAL.

Bug: 36220140
Test: check music/video playback, voice/VoIP
calls, OK google and  Camcorder with and without USB headset

Change-Id: Ic62b38fc9628c8ec44ddca17e82419be4f1e0fea