fbd-dev-leds: support for multicolor LEDs

Add support for multicolor LEDs as supported by the kernel.
Used by Qualcomm devices such as SHIFT 6mq, OnePlus 6, etc.

Documentation:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/ABI/testing/sysfs-class-led-multicolor

Co-Developed-by: Dylan Van Assche <me@dylanvanassche.be>
7 jobs for multicolor-v2 in 5 minutes and 15 seconds (queued for 5 seconds)