arm64: dts: rockchip: add extcon nodes and enable tcphy rk3399-gru

Enable tcphy and create the cros-ec's extcon node for the USB Type-C port.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>