ARM: dts: imx: 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/imx53-ppd.dt.yaml
CHECK arch/arm/boot/dts/imx53-ppd.dt.yaml
arch/arm/boot/dts/imx53-ppd.dt.yaml: leds-brightness: 'alarm-brightness' does not match any of the regexes: '^led(-[0-9a-f]+)?$', 'pinctrl-[0-9]+'
From schema: Documentation/devicetree/bindings/leds/leds-pwm.yaml
DTC arch/arm/boot/dts/imx6dl-cubox-i.dt.yaml
CHECK arch/arm/boot/dts/imx6dl-cubox-i.dt.yaml
arch/arm/boot/dts/imx6dl-cubox-i.dt.yaml: pwmleds: 'front' does not match any of the regexes: '^led(-[0-9a-f]+)?$', 'pinctrl-[0-9]+'
From schema: Documentation/devicetree/bindings/leds/leds-pwm.yaml
DTC arch/arm/boot/dts/imx6dl-cubox-i-emmc-som-v15.dt.yaml
CHECK arch/arm/boot/dts/imx6dl-cubox-i-emmc-som-v15.dt.yaml
arch/arm/boot/dts/imx6dl-cubox-i-emmc-som-v15.dt.yaml: pwmleds: 'front' does not match any of the regexes: '^led(-[0-9a-f]+)?$', 'pinctrl-[0-9]+'
From schema: Documentation/devicetree/bindings/leds/leds-pwm.yaml
DTC arch/arm/boot/dts/imx6dl-cubox-i-som-v15.dt.yaml
CHECK arch/arm/boot/dts/imx6dl-cubox-i-som-v15.dt.yaml
arch/arm/boot/dts/imx6dl-cubox-i-som-v15.dt.yaml: pwmleds: 'front' does not match any of the regexes: '^led(-[0-9a-f]+)?$', 'pinctrl-[0-9]+'
From schema: Documentation/devicetree/bindings/leds/leds-pwm.yaml
DTC arch/arm/boot/dts/imx6sx-softing-vining-2000.dt.yaml
CHECK arch/arm/boot/dts/imx6sx-softing-vining-2000.dt.yaml
arch/arm/boot/dts/imx6sx-softing-vining-2000.dt.yaml: pwmleds: 'blue', 'green', 'red' do not match any of the regexes: '^led(-[0-9a-f]+)?$', 'pinctrl-[0-9]+'
From schema: Documentation/devicetree/bindings/leds/leds-pwm.yaml

Signed-off-by: Alexander Dahl <[e-mail]>
Signed-off-by: Shawn Guo <[e-mail]>

arch/arm/boot/dts/imx53-ppd.dts

···
 		power-supply = <&reg_3v3_lcd>;
 	};
 
-	leds-brightness {
+	led-controller-1 {
 		compatible = "pwm-leds";
 
-		alarm-brightness {
+		led-1 {
+			label = "alarm-brightness";
 			pwms = <&pwm1 0 100000>;
 			max-brightness = <255>;
 		};
 	};
 
-	leds {
+	led-controller-2 {
 		compatible = "gpio-leds";
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_alarmled_pins>;
 
-		alarm1 {
+		led-2 {
 			label = "alarm:red";
 			gpios = <&gpio7 3 GPIO_ACTIVE_HIGH>;
 		};
 
-		alarm2 {
+		led-3 {
 			label = "alarm:yellow";
 			gpios = <&gpio7 7 GPIO_ACTIVE_HIGH>;
 		};
 
-		alarm3 {
+		led-4 {
 			label = "alarm:blue";
 			gpios = <&gpio7 8 GPIO_ACTIVE_HIGH>;
 		};
 
-		alarm4 {
+		led-5 {
 			label = "alarm:silenced";
 			gpios = <&gpio7 13 GPIO_ACTIVE_HIGH>;
 		};

arch/arm/boot/dts/imx6qdl-cubox-i.dtsi

···
 		pinctrl-0 = <&pinctrl_cubox_i_ir>;
 	};
 
-	pwmleds {
+	led-controller {
 		compatible = "pwm-leds";
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_cubox_i_pwm1>;
 
-		front {
+		led-1 {
 			active-low;
 			label = "imx6:red:front";
 			max-brightness = <248>;

arch/arm/boot/dts/imx6sx-softing-vining-2000.dts

···
 		regulator-max-microvolt = <3300000>;
 	};
 
-	pwmleds {
+	led-controller {
 		compatible = "pwm-leds";
 
-		red {
+		led-1 {
 			label = "red";
 			max-brightness = <255>;
 			pwms = <&pwm6 0 50000>;
 		};
 
-		green {
+		led-2 {
 			label = "green";
 			max-brightness = <255>;
 			pwms = <&pwm2 0 50000>;
 		};
 
-		blue {
+		led-3 {
 			label = "blue";
 			max-brightness = <255>;
 			pwms = <&pwm1 0 50000>;