ARM64: rockchip: add support for rk3399 SoC based evb

RK3399 is a SoC from Rockchip with dual-core Cortex-A72
and quad-core Cortex-A53 CPU. It supports two USB3.0
type-C ports and two USB2.0 EHCI ports. Other interfaces
are very much like RK3288, the DRAM are 32bit width address
and support address from 0 to 4GB-128MB range.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>