arm: mvebu: Add support for Thecus N2350 (Armada 385) board

Thecus N2350 is a NAS based on Marvell Armada 385 SoC.

Specification:

- Processor: Marvel MV88F6820 Dual Core at 1GHz
- 1 GiB DDR4 RAM
- 4MB Macronix mx25l3205d SPI flash
- 512MB Hynix H27U4G8F2DTR-BC NAND flash
- I2C
- 2x USB 3.0
- 1x GBE LAN port (PHY: Marvell 88E1510)
- 2x SATA (hot swap slots)
- 3x buttons
- 10x LEDS
- serial console

Signed-off-by: Tony Dinh <mibodhi@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>