boards: sam_v71_xult: add support for PHY driver

Update to dts file to use the generic MII PHY driver.

Signed-off-by: Arvin Farahmand <[email protected]>

Author: arvinf

boards/arm/sam_v71_xult/sam_v71_xult-common.dtsi

@@ -203,6 +203,17 @@ zephyr_udc0: &usbhs {
 
 &gmac {
 	status = "okay";
+
+	phy: phy {
+		compatible = "ethernet-phy";
+		status = "okay";
+		address = <0>;
+		mdio = <&mdio>;
+	};
+};
+
+&mdio {
+	status = "okay";
 };
 
 &pwm0 {