arm64: dts: imx8mq-evk: add missing MDIO / PHY nodes

Populate the fec1 node with the missing MDIO and PHY entries.
Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mq-evk.dts

@@ -37,7 +37,18 @@ &fec1 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_fec1>;
 	phy-mode = "rgmii-id";
+	phy-handle = <&ethphy0>;
 	status = "okay";
+
+	mdio {
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		ethphy0: ethernet-phy@0 {
+			compatible = "ethernet-phy-ieee802.3-c22";
+			reg = <0>;
+		};
+	};
 };
 
 &i2c1 {