ARM: dts: berlin: Fix schema warnings for pwm-leds

The node names for devices using the pwm-leds driver follow a certain
naming scheme (now).  Parent node name is not enforced, but recommended
by DT project.

  DTC     arch/arm/boot/dts/berlin2cd-google-chromecast.dt.yaml
  CHECK   arch/arm/boot/dts/berlin2cd-google-chromecast.dt.yaml
/home/alex/build/linux/arch/arm/boot/dts/berlin2cd-google-chromecast.dt.yaml: leds: 'red', 'white' do not match any of the regexes: '^led(-[0-9a-f]+)?$', 'pinctrl-[0-9]+'
        From schema: /home/alex/src/linux/leds/Documentation/devicetree/bindings/leds/leds-pwm.yaml
Signed-off-by: Alexander Dahl <post@lespocky.de>
Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>

arch/arm/boot/dts/berlin2cd-google-chromecast.dts

@@ -34,19 +34,19 @@ memory@0 {
 		linux,usable-memory = <0x00000000 0x20000000>; /* 512 MB */
 	};
 
-	leds {
+	led-controller {
 		compatible = "pwm-leds";
 		pinctrl-0 = <&ledpwm_pmux>;
 		pinctrl-names = "default";
 
-		white {
+		led-1 {
 			label = "white";
 			pwms = <&pwm 0 600000 0>;
 			max-brightness = <255>;
 			linux,default-trigger = "default-on";
 		};
 
-		red {
+		led-2 {
 			label = "red";
 			pwms = <&pwm 1 600000 0>;
 			max-brightness = <255>;