CONFIG_BLACKFIN is not available for thedefaultarchitecture x86.
Result is shown for architecture blackfin

CONFIG_BLACKFIN (not configurable)

modulename: blackfin-cpufreq.ko

configname: CONFIG_BLACKFIN

Linux Kernel Configuration
└─>BLACKFIN
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
source code:
drivers/cpufreq/blackfin-cpufreq.c