dt-bindings: leds: pwm-multicolor: Add active-low property

Add the active-low property to LEDs that are part of a multicolor LED
just like the regular PWM LEDs have.
Signed-off-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml

@@ -33,6 +33,10 @@ properties:
 
           pwm-names: true
 
+          active-low:
+            description: For PWMs where the LED is wired to supply rather than ground.
+            type: boolean
+
           color: true
 
         required: