CONFIG_DCLK_DIV is not available for thedefaultarchitecture x86.
Result is shown for architecture blackfin
default or selected kernelversion does not have config value CONFIG_DCLK_DIV.
Result is shown for kernelversion 6.7-rc3

DDR Clock Divider

configname: CONFIG_DCLK_DIV

Linux Kernel Configuration
└─>Blackfin Processor Options
└─>Board customizations
└─>DDR Clock Divider
In linux kernel since version 3.1 (release Date: 2011-10-24)  
This sets the frequency of the DDR memory.
This can be between 1 and 15
DDR Clock = (PLL frequency) / (this setting)