arm64: dts: rockchip: Add LED_GREEN for edgeble-neu6a

Edgeble NCM6A, NCM6B SoM has Green LED on the module.

Enable them with heartbeat function.

Signed-off-by: Jagan Teki <jagan@edgeble.ai>
Link: https://lore.kernel.org/r/20231125190522.87607-11-jagan@edgeble.ai


Signed-off-by: Heiko Stuebner <heiko@sntech.de>