arm64: dts: realtek: rtc16xx: add missing unit address to soc node

"soc" node has "ranges" property thus add matching unit address to fix
dtc W=1 warnings:

  rtd16xx.dtsi:130.6-198.4: Warning (unit_address_vs_reg): /soc: node has a reg or ranges property, but no unit name
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20240401140912.97157-3-krzk@kernel.org

arch/arm64/boot/dts/realtek/rtd16xx.dtsi

@@ -127,7 +127,7 @@ osc27M: osc {
 		#clock-cells = <0>;
 	};
 
-	soc {
+	soc@0 {
 		compatible = "simple-bus";
 		#address-cells = <1>;
 		#size-cells = <1>;