dt-bindings: leds: class-multicolor: Fix path to color definitions

The LED color definitions have always been in
include/dt-bindings/leds/common.h in upstream.

Fixes: 5c7f8ffe741daae7 ("dt: bindings: Add multicolor class dt bindings documention")
Signed-off-by: Geert Uytterhoeven <[e-mail]>
Acked-by: Conor Dooley <[e-mail]>
Link: https://lore.kernel.org/r/a3c7e[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

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

···
     description: |
       For multicolor LED support this property should be defined as either
       LED_COLOR_ID_RGB or LED_COLOR_ID_MULTI which can be found in
-      include/linux/leds/common.h.
+      include/dt-bindings/leds/common.h.
     enum: [ 8, 9 ]
 
 required: