arm64: dts: r8a7796: Mark EthernetAVB device node disabled

Device nodes representing I/O devices should be marked disabled in the
SoC-specific DTS, and overridden by board-specific DTSes where needed.

Fixes: 8e8b9eae ("arm64: dts: renesas: r8a7796: Add EthernetAVB instance")
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/r8a7796.dtsi

@@ -472,6 +472,7 @@
 			phy-mode = "rgmii-id";
 			#address-cells = <1>;
 			#size-cells = <0>;
+			status = "disabled";
 		};
 
 		scif2: serial@e6e88000 {