arm64: dts: mt7622: add port@5 as CPU port

On Banana Pi BPI-R64 and MediaTek MT7622 RFB1 board, port 5 of the MT7531
switch is connected to the second MAC of the SoC as a CPU port. Add the
port and set up the second MAC on the bindings.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Link: https://lore.kernel.org/r/20240219-for-mediatek-v1-1-7078f23eab82@arinc9.com
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

arch/arm64/boot/dts/mediatek/mt7622-bananapi-bpi-r64.dts

@@ -186,6 +186,18 @@
 					label = "lan3";
 				};
 
+				port@5 {
+					reg = <5>;
+					ethernet = <&gmac1>;
+					phy-mode = "rgmii";
+
+					fixed-link {
+						speed = <1000>;
+						full-duplex;
+						pause;
+					};
+				};
+
 				port@6 {
 					reg = <6>;
 					label = "cpu";

arch/arm64/boot/dts/mediatek/mt7622-rfb1.dts

@@ -118,6 +118,18 @@
 		};
 	};
 
+	gmac1: mac@1 {
+		compatible = "mediatek,eth-mac";
+		reg = <1>;
+		phy-mode = "rgmii";
+
+		fixed-link {
+			speed = <1000>;
+			full-duplex;
+			pause;
+		};
+	};
+
 	mdio-bus {
 		#address-cells = <1>;
 		#size-cells = <0>;
@@ -156,6 +168,18 @@
 					label = "wan";
 				};
 
+				port@5 {
+					reg = <5>;
+					ethernet = <&gmac1>;
+					phy-mode = "rgmii";
+
+					fixed-link {
+						speed = <1000>;
+						full-duplex;
+						pause;
+					};
+				};
+
 				port@6 {
 					reg = <6>;
 					label = "cpu";