arm64: dts: rockchip: Add support for Hugsun X99 TV Box

Add devicetree support for Hugsun X99 TV Box based on RK3399 SoC

Tested with LibreElec running kernel v5.1.2.
Following peripherals tested and work:

Peripheral works:
- UART2 debug
- eMMC
- USB 3.0 port
- USB 2.0 port
- sdio, sd-card
- HDMI
- Ethernet
- WiFi/BT

Not tested:
- Type-C port
- OPTICAL
- IR

Signed-off-by: Vivek Unune <npcomplete13@gmail.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>