CONFIG_CLOCK_FREQ is not available for thedefaultarchitecture x86.
Result is shown for architecture m68k

Set the core clock frequency

configname: CONFIG_CLOCK_FREQ

Linux Kernel Configuration
└─>Set the core clock frequency
In linux kernel since version 2.6.18 (release Date: 2006-09-19)  
Define the CPU clock frequency in use. This is the core clock
frequency, it may or may not be the same as the external clock
crystal fitted to your board. Some processors have an internal
PLL and can have their frequency programmed at run time, others
use internal dividers. In general the kernel won't setup a PLL
if it is fitted (there are some exceptions). This value will be
specific to the exact CPU that you are using.

depends
CONFIG_COLDFIRE