arm64: dts: rockchip: add sdmmc card detect to the nanopc-t6

The nanopc-t6 has an sdmmc card detect connected to gpio0_a4 which is
active low.
Signed-off-by: John Clark <inindev@gmail.com>
Link: https://lore.kernel.org/r/20231230165053.3781-1-inindev@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3588-nanopc-t6.dts

@@ -555,6 +555,7 @@ &sdmmc {
 	bus-width = <4>;
 	cap-mmc-highspeed;
 	cap-sd-highspeed;
+	cd-gpios = <&gpio0 RK_PA4 GPIO_ACTIVE_LOW>;
 	disable-wp;
 	no-mmc;
 	no-sdio;