arm64: allwinner: a64: Add initial Orangepi Win/WinPlus support

Orangepi Win/WinPlus is an open-source single-board computer
using the Allwinner A64 SOC.

A64 Orangepi Win/WinPlus has
- A64 Quad-core Cortex-A53 64bit
- 1GB(Win)/2GB(Win Plus) DDR3 SDRAM
- Debug TTL UART
- Four USB 2.0
- HDMI
- LCD
- Audio and MIC
- Wifi + BT
- IR receiver
- 5V DC power supply

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