CONFIG_MACH_DSMG600 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

D-Link DSM-G600 RevA

modulename: dsmg600-setup.ko

configname: CONFIG_MACH_DSMG600

Linux Kernel Configuration
└─>Intel IXP4xx Implementation Options
└─>D-Link DSM-G600 RevA
In linux kernel since version 2.6.22 (release Date: 2007-07-08)  
Say 'Y' here if you want your kernel to support D-Link's
DSM-G600 RevA device. For more information on this platform,
see http://www.nslu2-linux.org/wiki/DSMG600/HomePage

source code:
selects
CONFIG_PCI