CONFIG_S3C2412_CPUFREQ is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_S3C2412_CPUFREQ (not configurable)

modulename: cpu-freq.ko

and/or

cpufreq-s3c2412.ko

configname: CONFIG_S3C2412_CPUFREQ

Linux Kernel Configuration
└─>S3C2412_CPUFREQ
In linux kernel since version 2.6.32 (release Date: 2009-12-02)  
CPU Frequency scaling support for S3C2412 and S3C2413 SoC CPUs.

source code:
arch/arm/mach-s3c2412/cpu-freq.c