arm64: dts: rockchip: Add mt7531 dsa node to BPI-R2-Pro board

Add Device Tree node for mt7531 switch connected to gmac0.
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

arch/arm64/boot/dts/rockchip/rk3568-bpi-r2-pro.dts

@@ -394,6 +394,54 @@ &i2c5 {
 	status = "disabled";
 };
 
+&mdio0 {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	switch@0 {
+		compatible = "mediatek,mt7531";
+		reg = <0>;
+
+		ports {
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			port@1 {
+				reg = <1>;
+				label = "lan0";
+			};
+
+			port@2 {
+				reg = <2>;
+				label = "lan1";
+			};
+
+			port@3 {
+				reg = <3>;
+				label = "lan2";
+			};
+
+			port@4 {
+				reg = <4>;
+				label = "lan3";
+			};
+
+			port@5 {
+				reg = <5>;
+				label = "cpu";
+				ethernet = <&gmac0>;
+				phy-mode = "rgmii";
+
+				fixed-link {
+					speed = <1000>;
+					full-duplex;
+					pause;
+				};
+			};
+		};
+	};
+};
+
 &mdio1 {
 	rgmii_phy1: ethernet-phy@0 {
 		compatible = "ethernet-phy-ieee802.3-c22";