arm64: dts: rockchip: Enable SD card detection for Rock960 boards

For proper working of SD cards, let's add the Card Detect GPIO property
to the common devicetree for Rock960 family boards.
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3399-rock960.dtsi

@@ -439,6 +439,7 @@ &sdmmc {
 	cap-sd-highspeed;
 	clock-frequency = <100000000>;
 	clock-freq-min-max = <100000 100000000>;
+	cd-gpios = <&gpio0 7 GPIO_ACTIVE_LOW>;
 	disable-wp;
 	sd-uhs-sdr104;
 	vqmmc-supply = <&vcc_sd>;