arm64: dts: renesas: r8a779g0: Use MDIO node for all AVB devices

Switch from defining the PHY inside the AVB node itself and create a
dedicated MDIO node for AVB0, the only AVB describing a PHY.  This is
needed as adding PHYs to AVB1 and AVB2 will require setting MDIO bus
parameters and thus requires a dedicated node.
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20240413141806.300989-2-niklas.soderlund+renesas@ragnatech.seSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

arch/arm64/boot/dts/renesas/r8a779g0.dtsi

@@ -815,8 +815,6 @@ avb0: ethernet@e6800000 {
 			phy-mode = "rgmii";
 			rx-internal-delay-ps = <0>;
 			tx-internal-delay-ps = <0>;
-			#address-cells = <1>;
-			#size-cells = <0>;
 			status = "disabled";
 		};
 
@@ -862,8 +860,6 @@ avb1: ethernet@e6810000 {
 			phy-mode = "rgmii";
 			rx-internal-delay-ps = <0>;
 			tx-internal-delay-ps = <0>;
-			#address-cells = <1>;
-			#size-cells = <0>;
 			status = "disabled";
 		};
 
@@ -909,8 +905,6 @@ avb2: ethernet@e6820000 {
 			phy-mode = "rgmii";
 			rx-internal-delay-ps = <0>;
 			tx-internal-delay-ps = <0>;
-			#address-cells = <1>;
-			#size-cells = <0>;
 			status = "disabled";
 		};
 

arch/arm64/boot/dts/renesas/white-hawk-cpu-common.dtsi

@@ -142,18 +142,23 @@ reg_3p3v: regulator-3p3v {
 &avb0 {
 	pinctrl-0 = <&avb0_pins>;
 	pinctrl-names = "default";
-	phy-handle = <&phy0>;
+	phy-handle = <&avb0_phy>;
 	tx-internal-delay-ps = <2000>;
 	status = "okay";
 
-	phy0: ethernet-phy@0 {
-		compatible = "ethernet-phy-id0022.1622",
-			     "ethernet-phy-ieee802.3-c22";
-		rxc-skew-ps = <1500>;
-		reg = <0>;
-		interrupt-parent = <&gpio7>;
-		interrupts = <5 IRQ_TYPE_LEVEL_LOW>;
-		reset-gpios = <&gpio7 10 GPIO_ACTIVE_LOW>;
+	mdio {
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		avb0_phy: ethernet-phy@0 {
+			compatible = "ethernet-phy-id0022.1622",
+				     "ethernet-phy-ieee802.3-c22";
+			rxc-skew-ps = <1500>;
+			reg = <0>;
+			interrupt-parent = <&gpio7>;
+			interrupts = <5 IRQ_TYPE_LEVEL_LOW>;
+			reset-gpios = <&gpio7 10 GPIO_ACTIVE_LOW>;
+		};
 	};
 };