dt-bindings: input: pwm-vibrator: Add enable-gpio

Some pwm vibrators have a dedicated enable GPIO that needs to be set
high so that the vibrator works. Document that.

Signed-off-by: Luca Weiss <[e-mail]>
Reviewed-by: Sebastian Reichel <[e-mail]>
Reviewed-by: Brian Masney <[e-mail]>
Acked-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: Caleb Connolly <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Torokhov <[e-mail]>

Documentation/devicetree/bindings/input/pwm-vibrator.yaml

···
     minItems: 1
     maxItems: 2
 
+  enable-gpios: true
+
   vcc-supply: true
 
   direction-duty-cycle-ns: