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

D-Link Kirkwood-based NAS (Flattened Device Tree)

modulename: board-dnskw.ko

configname: CONFIG_MACH_DLINK_KIRKWOOD_DT

Linux Kernel Configuration
└─>Marvell Kirkwood Implementations
└─>D-Link Kirkwood-based 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
Kirkwood-based D-Link NASes such as DNS-320 & DNS-325,
using Flattened Device Tree.

source code: