ARM: dts: imx6dl-mamoj: Use #pwm-cells = <3> for imx27-pwm device

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

This fixes the following dtbs_check warning:

	arch/arm/boot/dts/nxp/imx/imx6dl-mamoj.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>

arch/arm/boot/dts/nxp/imx/imx6dl-mamoj.dts

@@ -21,7 +21,7 @@ memory@10000000 {
 
 	backlight_lcd: backlight-lcd {
 		compatible = "pwm-backlight";
-		pwms = <&pwm3 0 25000>; /* 25000ns -> 40kHz */
+		pwms = <&pwm3 0 25000 0>; /* 25000ns -> 40kHz */
 		brightness-levels = <0 4 8 16 32 64 128 160 192 224 255>;
 		default-brightness-level = <7>;
 	};
@@ -303,7 +303,6 @@ &ipu1_di0_disp0 {
 };
 
 &pwm3 {
-	#pwm-cells = <2>;
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_pwm3>;
 	status = "okay";