arm64: tegra: Enable MGBE on Jetson AGX Orin Developer Kit

A Multi-Gigabit Ethernet (MGBE) instance drives the primary Ethernet
port on the Jetson AGX Orin Developer Kit. Enable it.
Signed-off-by: Bhadram Varka <vbhadram@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm64/boot/dts/nvidia/tegra234-p3737-0000+p3701-0000.dts

@@ -2017,6 +2017,27 @@ chosen {
 		stdout-path = "serial0:115200n8";
 	};
 
+	bus@0 {
+		ethernet@6800000 {
+			status = "okay";
+
+			phy-handle = <&mgbe0_phy>;
+			phy-mode = "usxgmii";
+
+			mdio {
+				#address-cells = <1>;
+				#size-cells = <0>;
+
+				mgbe0_phy: phy@0 {
+					compatible = "ethernet-phy-ieee802.3-c45";
+					reg = <0x0>;
+
+					#phy-cells = <0>;
+				};
+			};
+		};
+	};
+
 	gpio-keys {
 		compatible = "gpio-keys";
 		status = "okay";