arm64: dts: rockchip: Designate Turing RK1's system power controller

Currently, the Turing RK1 board reboots when told to power off.

Resolve this by designating the RK806 as the system power controller, so
that the relevant driver can handle system shutdown requests.

Fixes: 2806a69f ("arm64: dts: rockchip: Add Turing RK1 SoM support")
Signed-off-by: Sam Edwards <CFSworks@gmail.com>
Link: https://lore.kernel.org/r/20240912180148.205957-1-CFSworks@gmail.com


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