arm: kirkwood: convert LaCie boards to DM_SPI_FLASH

This patch converts the following Kirkwood-based LaCie boards to DM,
DM_SPI and DM_SPI_FLASH:

- d2 Network v2
- Internet Space v2
- 2Big Network v2
- Network Space v2
- Network Space Lite v2
- Network Space Max v2
- Network Space Mini v2

Signed-off-by: Simon Guinot <simon.guinot@sequanux.org>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>