ARM: dts: sun9i: Add missing unit address

The soc node in the A80 DTSI has a ranges property, but no matching unit
address, which results in a DTC warning. Add the unit address to remove
that warning.
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

arch/arm/boot/dts/sun9i-a80.dtsi

@@ -289,7 +289,7 @@ de: display-engine {
 		status = "disabled";
 	};
 
-	soc {
+	soc@20000 {
 		compatible = "simple-bus";
 		#address-cells = <1>;
 		#size-cells = <1>;