dt-bindings: leds: Add Kinetic KTD2026/2027 LED

Document Kinetic KTD2026/2027 LED driver devicetree bindings.

Signed-off-by: André Apitzsch <git@apitzsch.eu>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20231002-ktd202x-v6-1-26be8eefeb88@apitzsch.eu


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