default or selected kernelversion does not have config value CONFIG_CLKSRC_OF.
Result is shown for kernelversion 6.5.1

CONFIG_CLKSRC_OF (not configurable)

modulename: clksrc-of.ko

configname: CONFIG_CLKSRC_OF

Linux Kernel Configuration
└─>Device Drivers
└─>CLKSRC_OF
In linux kernel since version 3.1 (release Date: 2011-10-24)  
source code:
drivers/clocksource/clksrc-of.c