sound: dt-bindings: Add USB audio QMI driver bindings

Add bindings for usb audio qmi service device. A remote entity
communicates with usb audio qmi server to enable or disable
particular audio stream on enumerated usb audio device.
This offloads ISOC data transfer operations to remote entity and
allows apps processor to go to power collapse more frequently for
better power saving.

Change-Id: I391dd45925799d364ab637a3050be61b7da6dbb1
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>