sun50i: h5: Add initial NanoPi NEO2 support

NanoPi NEO2 is designed and developed by FriendlyElec
using the Allwinner 64-bit H5 SOC.

NanoPi Neo2 key features
- Allwinner H5, Quad-core 64-bit Cortex-A53
- 512MB DDR3 RAM
- microSD slot
- 10/100/1000M Ethernet
- Serial Debug Port
- 5V 2A DC MicroUSB power-supply

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com>