arm64: tegra: Enable PCIe on Jetson TX2

Enable x4 PCIe slot on Jetson TX2.
Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
Tested-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm64/boot/dts/nvidia/tegra186-p2771-0000.dts

@@ -49,6 +49,30 @@ sdhci@3400000 {
 		vmmc-supply = <&vdd_sd>;
 	};
 
+	pcie@10003000 {
+		status = "okay";
+
+		dvdd-pex-supply = <&vdd_pex>;
+		hvdd-pex-pll-supply = <&vdd_1v8>;
+		hvdd-pex-supply = <&vdd_1v8>;
+		vddio-pexctl-aud-supply = <&vdd_1v8>;
+
+		pci@1,0 {
+			nvidia,num-lanes = <4>;
+			status = "okay";
+		};
+
+		pci@2,0 {
+			nvidia,num-lanes = <0>;
+			status = "disabled";
+		};
+
+		pci@3,0 {
+			nvidia,num-lanes = <1>;
+			status = "disabled";
+		};
+	};
+
 	gpio-keys {
 		compatible = "gpio-keys";