ARM: dts: sk-rzg1m: add Ether support

Define the SK-RZG1M board dependent part of the Ether device node.
Enable DHCP and NFS root  for the kernel booting.

Based on the original (and large) patch by Dmitry Shifrin
<dmitry.shifrin@cogentembedded.com>.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7743-sk-rzg1m.dts

@@ -20,7 +20,7 @@ aliases {
 	};
 
 	chosen {
-		bootargs = "ignore_loglevel";
+		bootargs = "ignore_loglevel rw root=/dev/nfs ip=dhcp";
 		stdout-path = "serial0:115200n8";
 	};
 
@@ -42,3 +42,16 @@ &extal_clk {
 &scif0 {
 	status = "okay";
 };
+
+&ether {
+	phy-handle = <&phy1>;
+	renesas,ether-link-active-low;
+	status = "okay";
+
+	phy1: ethernet-phy@1 {
+		reg = <1>;
+		interrupt-parent = <&irqc>;
+		interrupts = <0 IRQ_TYPE_LEVEL_LOW>;
+		micrel,led-mode = <1>;
+	};
+};