CONFIG_MACH_SMDKC100 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

SMDKC100

modulename: mach-smdkc100.ko

configname: CONFIG_MACH_SMDKC100

Linux Kernel Configuration
└─>SMDKC100
In linux kernel since version 2.6.32 (release Date: 2009-12-02)  
Machine support for the Samsung SMDKC100

source code:
arch/arm/mach-s5pc100/mach-smdkc100.c