CONFIG_MACH_NETSPACE_MINI_V2_DT is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

LaCie Network Space Mini v2 NAS (Flattened Device Tree)

modulename: board-ns2.ko

configname: CONFIG_MACH_NETSPACE_MINI_V2_DT

Linux Kernel Configuration
└─>Marvell Kirkwood Implementations
└─>LaCie Network Space Mini v2 NAS (Flattened Device Tree)
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Say 'Y' here if you want your kernel to support the LaCie
Network Space Mini v2 NAS using Flattened Device Tree.

This board is embedded in a product named CloudBox, which
provides automatic backup on a 100GB cloud storage. This
should not confused with a more recent LaCie NAS also named
CloudBox. For this last, the disk capacity is 1TB or above.

source code: