ARM: dts: imx: Use the correct mdio pattern

mdio-gpio is not a valid pattern according to mdio-gpio.yaml.

Use the generic 'mdio' name to fix the following dt-schema warnings:

'mdio-gpio' does not match '^mdio(-(bus|external))?(@.+|-([0-9]+))?$'

Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Author: Fabio Estevam

arch/arm/boot/dts/nxp/imx/imx51-zii-rdu1.dts

@@ -160,7 +160,7 @@
 		};
 	};
 
-	mdio_gpio: mdio-gpio {
+	mdio_gpio: mdio {
 		compatible = "virtual,mdio-gpio";
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_swmdio>;

arch/arm/boot/dts/nxp/imx/imx51-zii-scu2-mezz.dts

@@ -37,7 +37,7 @@
 		regulator-max-microvolt = <5000000>;
 	};
 
-	mdio_gpio: mdio-gpio {
+	mdio_gpio: mdio {
 		compatible = "virtual,mdio-gpio";
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_swmdio>;

arch/arm/boot/dts/nxp/imx/imx6q-bx50v3.dtsi

@@ -94,7 +94,7 @@
 		mdio-gpio0 = &mdio0;
 	};
 
-	mdio0: mdio-gpio {
+	mdio0: mdio {
 		compatible = "virtual,mdio-gpio";
 		gpios = <&gpio2 5 GPIO_ACTIVE_HIGH>, /* mdc */
 			<&gpio2 7 GPIO_ACTIVE_HIGH>; /* mdio */