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

The PCIe signals are routed through the connector to the baseboard.

Signed-off-by: Vicente Bergas <vicencb@gmail.com>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>