arm64: dts: rockchip: add PCIe network controller to rock-5b

Enable the RTL8125 network controller, which is connected via
PCIe.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20230918141451.131247-2-sebastian.reichel@collabora.com


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