CONFIG_CPU_L2CACHE_DISABLE is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_CPU_L2CACHE_DISABLE.
Result is shown for kernelversion 5.11.21

Disable level 2 cache

configname: CONFIG_CPU_L2CACHE_DISABLE

Linux Kernel Configuration
└─>Disable level 2 cache
In linux kernel since version 2.6.22 (release Date: 2007-07-08)  
Say Y here to disable the level 2 cache. If unsure, say N.

depends
CONFIG_CPU_V7