arm64: mvebu: Armada 3700: Add ethernet device tree nodes

This patch adds the ethernet device tree nodes that are still missing to
the Armada 3700 dts files.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Nadav Haklai <nadavh@marvell.com>
Cc: Kostya Porotchkin <kostap@marvell.com>
Cc: Wilson Ding <dingwei@marvell.com>
Cc: Victor Gu <xigu@marvell.com>
Cc: Hua Jing <jinghua@marvell.com>
Cc: Terry Zhou <bjzhou@marvell.com>
Cc: Hanna Hawa <hannah@marvell.com>
Cc: Haim Boot <hayim@marvell.com>
diff --git a/arch/arm/dts/armada-3720-db.dts b/arch/arm/dts/armada-3720-db.dts
index 7bfa840..2cc99bf 100644
--- a/arch/arm/dts/armada-3720-db.dts
+++ b/arch/arm/dts/armada-3720-db.dts
@@ -57,6 +57,7 @@
 	};
 
 	aliases {
+		ethernet0 = &eth0;
 		spi0 = &spi0;
 	};
 
@@ -66,6 +67,11 @@
 	};
 };
 
+&eth0 {
+	status = "okay";
+	phy-mode = "rgmii";
+};
+
 /* CON3 */
 &sata {
 	status = "okay";