CONFIG_MACH_NAS4220B is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Raidsonic NAS-4220-B

modulename: board-nas4220b.ko

configname: CONFIG_MACH_NAS4220B

Linux Kernel Configuration
└─>Cortina Systems Gemini Implementations
└─>Raidsonic NAS-4220-B
In linux kernel since version 2.6.36 (release Date: 2010-10-20)  
Say Y here if you intend to run this kernel on a
Raidsonic NAS-4220-B.

source code:
arch/arm/mach-gemini/board-nas4220b.c