ARC: [plat-arcfpga] Enable arc_emac for ARCAngle4 Board

* Add arc_emac to DeviceTree DT description
  "Documentation/devicetree/bindings/net/arc_emac.txt".

* Update defconfig correspondingly

[vgupta: tweaked changelog]
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/boot/dts/angel4.dts

@@ -51,5 +51,21 @@
 			current-speed = <115200>;
 			status = "okay";
 		};
+
+		ethernet@c0fc2000 {
+			compatible = "snps,arc-emac";
+			reg = <0xc0fc2000 0x3c>;
+			interrupts = <6>;
+			mac-address = [ 00 11 22 33 44 55 ];
+			clock-frequency = <80000000>;
+			max-speed = <100>;
+			phy = <&phy0>;
+
+			#address-cells = <1>;
+			#size-cells = <0>;
+			phy0: ethernet-phy@0 {
+				reg = <1>;
+			};
+		};
 	};
 };