dt-bindings: pwm: google,cros-ec: Do not require pwm-cells twice

pwm-cells property is already required by pwm.yaml schema.

Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/231df058d9cb35cfcf4bcdf4385f4ad8cb21a046.1714450308.git.zhoubinbin@loongson.cn
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Author: AaronDot

Documentation/devicetree/bindings/pwm/google,cros-ec-pwm.yaml

@@ -35,7 +35,6 @@ properties:
 
 required:
   - compatible
-  - '#pwm-cells'
 
 additionalProperties: false