board: sun50i: h6: Add OrangePi One Plus initial support

OrangePi One Plus is Allwinner H6 based open-source SBC,
which support:
- Allwinner H6 Quad-core 64-bit ARM Cortex-A53
- GPU Mali-T720
- 1GB LPDDR3 RAM
- AXP805 PMIC
- 1Gbps GMAC via RTL8211
- USB 2.0 Host, OTG
- HDMI port
- 5V/2A DC power supply

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>