arm: kirkwood: add ZyXEL NSA310S device

arm: kirkwood: add ZyXEL NSA310S device

This patch add ZyXEL NSA310S 1-Bay Media Server

The ZyXEL NSA310S device is a Kirkwood based NAS:

- SoC: Marvell 88F6702 1000Mhz
- SDRAM memory: 256MB DDR2 400Mhz
- Gigabit ethernet: PHY Marvell 88E1318
- Flash memory: 128MB
- 1 Power button
- 1 Power LED (blue)
- 4 Status LED (green)
- 1 Copy/Sync button
- 1 Reset button
- 1 SATA II port
- 2 USB 2.0 ports (front and back)
- Smart fan

Signed-off-by: Gerald Kerma <dreagle@doukki.net>
Signed-off-by: Tony Dinh <mibodhi@gmail.com>
Signed-off-by: Luka Perkov <luka.perkov@sartura.hr>