dt-bindings: usb: Add RK3588 EHCI

Add compatible for RK3588 EHCI. As far as I know it's fully
compatible with generic-ehci.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20230522162937.53190-3-sebastian.reichel@collabora.com


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