arm64: dts: imx8mp-venice-gw73xx: add mac addr for eth1

The SoM used on this board does not bring down the pins for the QOS
ethernet and instead offers the 2nd ethernet as a PCI GbE device.

Set the alias as such and add the PCI bus topology for eth1 so that
boot firmware can set the local-mac-address property.

The eth1 device is behind a PCI switch:
 # lspci -n
 00:00.0 0604: 16c3:abcd (rev 01)
 01:00.0 0604: 12d8:2608
 02:01.0 0604: 12d8:2608
 02:02.0 0604: 12d8:2608
 02:03.0 0604: 12d8:2608
 02:04.0 0604: 12d8:2608
 c0:00.0 0200: 1055:7430 (rev 11)
 # lspci -t
 -[0000:00]---00.0-[01-ff]----00.0-[02-fe]--+-01.0-[03-41]--
                                           +-02.0-[42-80]--
                                           +-03.0-[81-bf]--
                                           \-04.0-[c0-fe]----00.0
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mp-venice-gw73xx.dtsi

@@ -8,6 +8,10 @@
 #include <dt-bindings/phy/phy-imx8-pcie.h>
 
 / {
+	aliases {
+		ethernet1 = &eth1;
+	};
+
 	connector {
 		compatible = "gpio-usb-b-connector", "usb-b-connector";
 		pinctrl-names = "default";
@@ -163,6 +167,38 @@ &pcie {
 	pinctrl-0 = <&pinctrl_pcie0>;
 	reset-gpio = <&gpio4 29 GPIO_ACTIVE_LOW>;
 	status = "okay";
+
+	pcie@0,0 {
+		reg = <0x0000 0 0 0 0>;
+		device_type = "pci";
+		#address-cells = <3>;
+		#size-cells = <2>;
+		ranges;
+
+		pcie@0,0 {
+			reg = <0x0000 0 0 0 0>;
+			device_type = "pci";
+			#address-cells = <3>;
+			#size-cells = <2>;
+			ranges;
+
+			pcie@4,0 {
+				reg = <0x2000 0 0 0 0>;
+				device_type = "pci";
+				#address-cells = <3>;
+				#size-cells = <2>;
+				ranges;
+
+				eth1: ethernet@0,0 {
+					reg = <0x0000 0 0 0 0>;
+					#address-cells = <3>;
+					#size-cells = <2>;
+					ranges;
+					local-mac-address = [00 00 00 00 00 00];
+				};
+			};
+		};
+	};
 };
 
 /* GPS */