[ARM] Kirkwood: add LaCie Internet Space v2 support

The Internet and Network Space v2 boards are very close. The only
difference is that there is no USB type B plug wired on the Internet
Space v2.

Signed-off-by: Simon Guinot <sguinot@lacie.com>
Signed-off-by: Nicolas Pitre <nico@marvell.com>