dt-bindings: usb: dwc2: rockchip: add rockchip,rk3128-usb

Add rockchip,rk3128-usb compatible string.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/dfb657ab-85e5-ac47-810d-133c7e8dd823@gmail.com


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