arm: mvebu: enable Ethernet controllers on Mirabox platform

The Globalscale Mirabox platform has two Ethernet interfaces,
connected to the SoC with a RGMII interface.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

arch/arm/boot/dts/armada-370-mirabox.dts

@@ -33,5 +33,26 @@ timer@d0020300 {
 			clock-frequency = <600000000>;
 			status = "okay";
 		};
+		mdio {
+			phy0: ethernet-phy@0 {
+				reg = <0>;
+			};
+
+			phy1: ethernet-phy@1 {
+				reg = <1>;
+			};
+		};
+		ethernet@d0070000 {
+			clock-frequency = <200000000>;
+			status = "okay";
+			phy = <&phy0>;
+			phy-mode = "rgmii-id";
+		};
+		ethernet@d0074000 {
+			clock-frequency = <200000000>;
+			status = "okay";
+			phy = <&phy1>;
+			phy-mode = "rgmii-id";
+		};
 	};
 };