default or selected kernelversion does not have config value CONFIG_GCC_PLUGIN_CYC_COMPLEXITY.
Result is shown for kernelversion 6.9.5

Compute the cyclomatic complexity of a function

configname: CONFIG_GCC_PLUGIN_CYC_COMPLEXITY

Linux Kernel Configuration
└─>General architecture-dependent options
└─>GCC plugins
└─>Compute the cyclomatic complexity of a function
In linux kernel since version 4.1 (release Date: 2015-06-21)  
The complexity M of a function's control flow graph is defined as:
M = E - N + 2P
where

E = the number of edges
N = the number of nodes
P = the number of connected components (exit nodes).

Enabling this plugin reports the complexity to stderr during the
build. It mainly serves as a simple example of how to create a
gcc plugin for the kernel.

depends
CONFIG_GCC_PLUGINS
NOT CONFIG_COMPILE_TEST