dt-bindings: usb: samsung,exynos-dwc3 Add exynos990 compatible

Add a compatible for the exynos990-dwusb3 node. It's compatible with the
exynos850 variant when using the highspeed mode.

Signed-off-by: Igor Belwon <igor.belwon@mentallysanemainliners.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20250217-exynos990-bindings-usb3-v2-1-3b3f0809f4fb@mentallysanemainliners.org


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