arm64: tegra: Disable SD card write-protection on Jetson Nano

There is no GPIO hooked up to the write-protection pin of the SD slot.
Make sure to describe this properly in device tree to avoid errors or
warnings being emitted by the operating system.
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm64/boot/dts/nvidia/tegra210-p3450-0000.dts

@@ -576,6 +576,7 @@ mmc@700b0000 {
 		bus-width = <4>;
 
 		cd-gpios = <&gpio TEGRA_GPIO(Z, 1) GPIO_ACTIVE_LOW>;
+		disable-wp;
 
 		vqmmc-supply = <&vddio_sdmmc>;
 		vmmc-supply = <&vdd_3v3_sd>;