arm64: dts: rockchip: configure PCIe support for rk3399-evb

Let's assigne slot numbers, ep-gpios and clkreq used by PCIe
on evb board as well the PHY node here. Note that we still
disable them as the auto training of PCIe link will make the
kernel use more time to boot if there are no any devices there.

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