ARM: dts: r8a7790: use fallback etheravb compatibility string

Use recently added fallback compatibility string in r8a7790 device tree.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>

arch/arm/boot/dts/r8a7790.dtsi

@@ -773,7 +773,8 @@ ether: ethernet@ee700000 {
 	};
 
 	avb: ethernet@e6800000 {
-		compatible = "renesas,etheravb-r8a7790";
+		compatible = "renesas,etheravb-r8a7790",
+			     "renesas,etheravb-rcar-gen2";
 		reg = <0 0xe6800000 0 0x800>, <0 0xee0e8000 0 0x4000>;
 		interrupts = <GIC_SPI 163 IRQ_TYPE_LEVEL_HIGH>;
 		clocks = <&mstp8_clks R8A7790_CLK_ETHERAVB>;