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

kselftests for DRM

modulename: test-drm_mm.ko


Linux Kernel Configuration
└─>Device Drivers
└─>Graphics support
└─>Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)
└─>kselftests for DRM
In linux kernel since version 4.2 (release Date: 2015-08-30)  
This option provides kernel modules that can be used to run
various selftests on parts of the DRM api. This option is not
useful for distributions or general kernels, but only for kernel
developers working on DRM and associated drivers.

If in doubt, say "N".

source code: