dt-bindings: leds: Optional multi-led unit address

The unit address does not make sense in all cases the multi-led node is
used, e.g. for the upcoming PWM multi-color LED driver.
Signed-off-by: Sven Schwermer <sven.schwermer@disruptive-technologies.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

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

@@ -20,7 +20,7 @@ description: |
   within this documentation directory.
 
 patternProperties:
-  "^multi-led@([0-9a-f])$":
+  "^multi-led(@[0-9a-f])?$":
     type: object
     description: Represents the LEDs that are to be grouped.
     properties: