dt-bindings: usb: dwc3: Add the Amlogic A1 Family DWC3 Glue Bindings

The Amlogic A1 SoC Family embeds 1 USB Controllers:
 - a DWC3 IP configured as Host for USB2 and USB3

A glue connects the controllers to the USB2 PHY of A1 SoC.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Yue Wang <yue.wang@amlogic.com>
Signed-off-by: Hanjie Lin <hanjie.lin@amlogic.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>