CONFIG_MACH_NAS100D is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

NAS100D

modulename: nas100d-setup.ko

configname: CONFIG_MACH_NAS100D

Linux Kernel Configuration
└─>Intel IXP4xx Implementation Options
└─>NAS100D
In linux kernel since version 2.6.16 (release Date: 2006-03-19)  
Say 'Y' here if you want your kernel to support Iomega's
NAS 100d device. For more information on this platform,
see http://www.nslu2-linux.org/wiki/NAS100d/HomePage

source code: