ARM: dts: berlin2cd: add a label for the CPU node

This is useful if the board file needs to reference it.
Signed-off-by: Alexander Monakov <amonakov@ispras.ru>
Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>

arch/arm/boot/dts/berlin2cd.dtsi

@@ -57,7 +57,7 @@ cpus {
 		#address-cells = <1>;
 		#size-cells = <0>;
 
-		cpu@0 {
+		cpu: cpu@0 {
 			compatible = "arm,cortex-a9";
 			device_type = "cpu";
 			next-level-cache = <&l2>;