arm64: dts: rockchip: add support for Firefly ROC-RK3399-PC-PLUS

arm64: dts: rockchip: add support for Firefly ROC-RK3399-PC-PLUS

ROC-RK3399-PC-PLUS is the board inside the portable Firefly Station P1 Geek
PC. As a redesign after the ROC-RK3399-PC, it uses DC-12V as power input
and spares a USB 3 host port. It is also equipped with a USB WiFi chip and
audio codec without the mezzanine board.

- Rockchip RK3399 SoC
- 4GB LPDDR4 RAM
- 16MB SPI-Flash
- eMMC slot
- TF card slot
- USB 3.0 Port x 1, USB 2.0 Port x 1, TypeC Port x 1
- HDMI
- Gigabit Ethernet
- WiFi: RTL8723DU
- Audio: ES8388
- Key: Recovery
- LED: WORK, DIY
- IR

Signed-off-by: Kongxin Deng <dkx@t-chip.com.cn>
Signed-off-by: Levin Du <djw@t-chip.com.cn>
Link: https://lore.kernel.org/r/20210628035402.16812-3-djw@t-chip.com.cn
Signed-off-by: Heiko Stuebner <heiko@sntech.de>