ARM: dts: rmobile: Add soc label to Gen3

Add label to the /soc node, so it can be referenced from the U-Boot DTs.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
---
V2: Rebase on u-boot/master
diff --git a/arch/arm/dts/r8a77965.dtsi b/arch/arm/dts/r8a77965.dtsi
index 7a5d68b..f28a82c 100644
--- a/arch/arm/dts/r8a77965.dtsi
+++ b/arch/arm/dts/r8a77965.dtsi
@@ -144,7 +144,7 @@
 				     <&a57_1>;
 	};
 
-	soc {
+	soc: soc {
 		compatible = "simple-bus";
 		interrupt-parent = <&gic>;
 		#address-cells = <2>;