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.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>