The binding doesn't define interrupts and adding such a definition was
refused because it's unclear how they should ever be used and the
relevant registers are outside the PWM range. So drop them fixing
several dtbs_check warnings like:

	arch/arm/boot/dts/rockchip/rv1108-elgin-r1.dtb: pwm@10280030: 'interrupts' does not match any of the regexes: 'pinctrl-[0-9]+'
	from schema $id: http://devicetree.org/schemas/pwm/pwm-rockchip.yaml#Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20240129113205.2453029-2-u.kleine-koenig@pengutronix.deSigned-off-by: Heiko Stuebner <heiko@sntech.de>