leds: Add ktd202x driver

This commit adds support for Kinetic KTD2026/7 RGB/White LED driver.

Signed-off-by: André Apitzsch <git@apitzsch.eu>
Link: https://lore.kernel.org/r/20231002-ktd202x-v6-2-26be8eefeb88@apitzsch.eu


Signed-off-by: Lee Jones <lee@kernel.org>