default or selected kernelversion does not have config value CONFIG_ET131X_DEBUG.
Result is shown for kernelversion 6.2.5

Enable et131x debugging

configname: CONFIG_ET131X_DEBUG

Linux Kernel Configuration
└─>Device Drivers
└─>Staging drivers
└─>Enable et131x debugging
In linux kernel since version 2.6.28 (release Date: 2008-12-24)  
Say Y for detailed debug information.

If in doubt, say N.