CONFIG_MACH_IB62X0_DT is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

RaidSonic IB-NAS6210, IB-NAS6220 (Flattened Device Tree)

modulename: board-ib62x0.ko

configname: CONFIG_MACH_IB62X0_DT

Linux Kernel Configuration
└─>Marvell Kirkwood Implementations
└─>RaidSonic IB-NAS6210, IB-NAS6220 (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
RaidSonic IB-NAS6210 & IB-NAS6220 devices, using
Flattened Device Tree.

source code:
arch/arm/mach-kirkwood/board-ib62x0.c