default or selected kernelversion does not have config value CONFIG_DST_DEBUG.
Result is shown for kernelversion 5.4.159

DST debug

configname: CONFIG_DST_DEBUG

Linux Kernel Configuration
└─>Device Drivers
└─>Staging drivers
└─>DST debug
In linux kernel since version 2.6.30 (release Date: 2009-06-09)  
This option will enable HEAVY debugging of the DST.
Turn it on ONLY if you have to debug some really obscure problem.