arm64: dts: rockchip: move rk3399-sapphire sdio to excavator baseboard

The sdio signals are routed through the connector to the baseboard,
where the wifi module is also located. So move the sdio node to
the excavator as well.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Vicente Bergas <vicencb@gmail.com>