ARM: kirkwood: DT board setup for Network Space Lite v2

This patch adds DT board setup for the LaCie NAS Network Space Lite v2.
This board is derived from the Network Space v2 and a lot of hardware
characteristics are shared.

- CPU: Marvell 88F6192 800Mhz
- SDRAM memory: 128MB DDR2 200Mhz
- 1 SATA port: internal
- Gigabit ethernet: PHY Marvell 88E1318
- Flash memory: SPI NOR 512KB (Macronix MX25L4005A)
- i2c EEPROM: 512 bytes (24C04 type)
- 2 USB2 ports: host and host/device
- 1 push button
- 1 SATA LED (bi-color, blue and red)

Note that the SATA LED is not compatible with the driver leds-ns2. The
LED behaviour ("on", "off" or "SATA activity blink") is controlled via
a single MPP (21).

Signed-off-by: Simon Guinot <simon.guinot@sequanux.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>