ARM: dts: berlin2: Add missing unit name to /soc node

This patch fixes the following DTC warning with W=1:

"Node /soc has a reg or ranges property, but no unit name"
Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>

arch/arm/boot/dts/berlin2.dtsi

@@ -90,7 +90,7 @@ refclk: oscillator {
 		clock-frequency = <25000000>;
 	};
 
-	soc {
+	soc@f7000000 {
 		compatible = "simple-bus";
 		#address-cells = <1>;
 		#size-cells = <1>;