CONFIG_METAG_DSP is not available for thedefaultarchitecture x86.
Result is shown for architecture metag
default or selected kernelversion does not have config value CONFIG_METAG_DSP.
Result is shown for kernelversion 6.7-rc3

DSP Support

configname: CONFIG_METAG_DSP

Linux Kernel Configuration
└─>Processor type and features
└─>DSP Support
In linux kernel since version 3.1 (release Date: 2011-10-24)  
This option allows processes to use DSP hardware available
with this CPU. If this option is not enabled DSP registers
will not be saved and restored on context-switch.

If you plan on running DSP programs say Y here.