ARM: shmobile: r8a7790: add EtherAVB DT support

Define the generic R8A7790 part of the EtherAVB device node.

Based on original patch by Mitsuhiro Kimura <mitsuhiro.kimura.kc@renesas.com>.
Signed-off-by: NSergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7790.dtsi

@@ -671,6 +671,16 @@
 		status = "disabled";
 	};
 
+	avb: ethernet@e6800000 {
+		compatible = "renesas,etheravb-r8a7790";
+		reg = <0 0xe6800000 0 0x800>, <0 0xee0e8000 0 0x4000>;
+		interrupts = <0 163 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&mstp8_clks R8A7790_CLK_ETHERAVB>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		status = "disabled";
+	};
+
 	sata0: sata@ee300000 {
 		compatible = "renesas,sata-r8a7790";
 		reg = <0 0xee300000 0 0x2000>;