dt-bindings: mmc: rockchip-dw-mshc: Add RK3588 compatible string

Add RK3588 compatible string for SD interface.

Co-developed-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Lucas Tanure <lucas.tanure@collabora.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20230213152740.359055-1-lucas.tanure@collabora.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>