ARM: dts: imx6ul-pico: Use #pwm-cells = <3> for imx27-pwm device

The binding dictates using 3 pwm-cells. Adhere to that.

This fixes the following dtbs_check warnings:

	arch/arm/boot/dts/nxp/imx/imx6ul-pico-dwarf.dtb: pwm@2088000: #pwm-cells:0:0: 3 was expected
		from schema : http://devicetree.org/schemas/pwm/imx-pwm.yaml#
	arch/arm/boot/dts/nxp/imx/imx6ul-pico-hobbit.dtb: pwm@2088000: #pwm-cells:0:0: 3 was expected
		from schema : http://devicetree.org/schemas/pwm/imx-pwm.yaml#
	arch/arm/boot/dts/nxp/imx/imx6ul-pico-pi.dtb: pwm@2088000: #pwm-cells:0:0: 3 was expected
		from schema : http://devicetree.org/schemas/pwm/imx-pwm.yaml#

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Author: Uwe Kleine-König

arch/arm/boot/dts/nxp/imx/imx6ul-pico.dtsi

@@ -22,7 +22,7 @@
 
 	backlight: backlight {
 		compatible = "pwm-backlight";
-		pwms = <&pwm3 0 5000000>;
+		pwms = <&pwm3 0 5000000 0>;
 		brightness-levels = <0 4 8 16 32 64 128 255>;
 		default-brightness-level = <6>;
 		status = "okay";
@@ -177,7 +177,6 @@
 };
 
 &pwm3 {
-	#pwm-cells = <2>;
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_pwm3>;
 	status = "okay";