On Edgeble Neural Compute Module add system-power-controller
property to RK806 pmic so that these chips can power off the device.

Cc: Jagan Teki <jagan@edgeble.ai>
Signed-off-by: Anand Moon <anand@edgeble.ai>
Link: https://lore.kernel.org/r/20240502094246.4695-1-anand@edgeble.aiSigned-off-by: Heiko Stuebner <heiko@sntech.de>