usb: xhci-rockchip: add rockchip dwc3 controller driver

This patch add support for rockchip dwc3 controller, which corresponding
to the two type-C port on rk3399 evb.
Only support usb2.0 currently for we have not enable the usb3.0 phy
driver and PD(fusb302) driver.

Signed-off-by: MengDongyang <daniel.meng@rock-chips.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>