arm64: dts: realtek: rtd129x: add missing unit address to soc node

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

  rtd129x.dtsi:51.6-122.4: 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/20240401140912.97157-1-krzk@kernel.org

arch/arm64/boot/dts/realtek/rtd129x.dtsi

@@ -48,7 +48,7 @@ osc27M: osc {
 		clock-output-names = "osc27M";
 	};
 
-	soc {
+	soc@0 {
 		compatible = "simple-bus";
 		#address-cells = <1>;
 		#size-cells = <1>;