dt-bindings: usb: dwc2: add compatible for RK3308 USB controller

The USB controller in the RK3308 is compatible with the RK3066 USB
controller.
This patch adds a compatible string for it.
Signed-off-by: Tobias Schramm <t.schramm@manjaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210514150044.2099298-4-t.schramm@manjaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/dwc2.yaml

@@ -24,6 +24,7 @@ properties:
               - rockchip,rk3188-usb
               - rockchip,rk3228-usb
               - rockchip,rk3288-usb
+              - rockchip,rk3308-usb
               - rockchip,rk3328-usb
               - rockchip,rk3368-usb
               - rockchip,rv1108-usb