mips: dts: ralink: mt7621: add mdio label to mdio-bus

Add mdio label to the mdio-bus node to easily refer to it.

Use the newly created label on the GB-PC2 devicetree.
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Reviewed-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/boot/dts/ralink/mt7621-gnubee-gb-pc2.dts

@@ -93,18 +93,16 @@ gpio-pinmux {
 	};
 };
 
-&ethernet {
-	gmac1: mac@1 {
+&gmac1 {
 	status = "okay";
 	phy-handle = <&ethphy7>;
-	};
+};
 
-	mdio-bus {
+&mdio {
 	ethphy7: ethernet-phy@7 {
 		reg = <7>;
 		phy-mode = "rgmii-rxid";
 	};
-	};
 };
 
 &switch0 {

arch/mips/boot/dts/ralink/mt7621.dtsi

@@ -342,7 +342,7 @@ gmac1: mac@1 {
 			phy-mode = "rgmii-rxid";
 		};
 
-		mdio-bus {
+		mdio: mdio-bus {
 			#address-cells = <1>;
 			#size-cells = <0>;