arm64: dts: rockchip: Add VMARC RK3399Pro SOM initial support

arm64: dts: rockchip: Add VMARC RK3399Pro SOM initial support

VMARC RK3399Pro SOM is a standard SMARC SOM design with
Rockchip RK3399Pro SoC, which is designed by Vamrs.

Specification:
- Rockchip RK3399Pro
- PMIC: RK809-3
- SD slot, 16GiB eMMC
- 2xUSB-2.0, 1xUSB3.0
- USB-C for power supply
- Ethernet, PCIe
- HDMI, MIPI-DSI/CSI, eDP

Add initial support for VMARC RK3399Pro SOM, this would use
with associated carrier board.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Link: https://lore.kernel.org/r/20191216174711.17856-3-jagan@amarulasolutions.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>