arm64: dts: rockchip: Remove undocumented sdmmc property from lubancat-1

arm64: dts: rockchip: Remove undocumented sdmmc property from lubancat-1

Property "supports-sd" isn't documented anywhere and is unnecessary for
mainline driver to function. It seems a property used by downstream
kernel was brought into mainline.

This should be reported by dtbs_check, but mmc-controller-common.yaml
defaults additionalProperties to true thus allows it. Remove the
property to clean the devicetree up and avoid possible confusion.

Fixes: 8d94da58de53 ("arm64: dts: rockchip: Add EmbedFire LubanCat 1")
Signed-off-by: Yao Zi <ziyao@disroot.org>
Link: https://lore.kernel.org/r/20250228163117.47318-2-ziyao@disroot.org
Signed-off-by: Heiko Stuebner <heiko@sntech.de>