arm64: dts: allwinner: h5: Add cpu0 label for first cpu

At the board level, we want to be able to specify what regulator
supplies power to the cpu domain.

Add a label to the first cpu node so we can reference it later.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

arch/arm64/boot/dts/allwinner/sun50i-h5.dtsi

@@ -47,7 +47,7 @@ cpus {
 		#address-cells = <1>;
 		#size-cells = <0>;
 
-		cpu@0 {
+		cpu0: cpu@0 {
 			compatible = "arm,cortex-a53", "arm,armv8";
 			device_type = "cpu";
 			reg = <0>;