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

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 <geert+renesas@glider.be>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/a3c7ea92e90b77032f2e480d46418b087709286d.1731588129.git.geert+renesas@glider.be
Signed-off-by: Lee Jones <lee@kernel.org>