CONFIG_MACH_RD88F6192_NAS is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Marvell RD-88F6192-NAS Reference Board

modulename: rd88f6192-nas-setup.ko

configname: CONFIG_MACH_RD88F6192_NAS

Linux Kernel Configuration
└─>Marvell Kirkwood Implementations
└─>Marvell RD-88F6192-NAS Reference Board
In linux kernel since version 2.6.27 (release Date: 2008-10-09)  
Say 'Y' here if you want your kernel to support the
Marvell RD-88F6192-NAS Reference Board.

source code:
arch/arm/mach-kirkwood/rd88f6192-nas-setup.c