ARM: dts: imx6qdl-gw52xx: Use #pwm-cells = <3> for imx27-pwm device

ARM: dts: imx6qdl-gw52xx: 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/imx6dl-gw52xx.dtb: pwm@208c000: #pwm-cells:0:0: 3 was expected
		from schema : http://devicetree.org/schemas/pwm/imx-pwm.yaml#
	arch/arm/boot/dts/nxp/imx/imx6q-gw52xx.dtb: pwm@208c000: #pwm-cells:0:0: 3 was expected
		from schema : http://devicetree.org/schemas/pwm/imx-pwm.yaml#

Signed-off-by: Uwe Kleine-König <[email protected]>
Signed-off-by: Shawn Guo <[email protected]>