CONFIG_RISCV_ISA_ZICBOM is not available for thedefaultarchitecture x86.
Result is shown for architecture riscv

Zicbom extension support for non-coherent DMA operation

configname: CONFIG_RISCV_ISA_ZICBOM

Linux Kernel Configuration
└─>Platform type
└─>Zicbom extension support for non-coherent DMA operation
In linux kernel since version 4.14.326 (release Date: 2023-09-23)  
Add support for the Zicbom extension (Cache Block Management
Operations) and enable its use in the kernel when it is detected
at boot.

The Zicbom extension can be used to handle for example
non-coherent DMA support on devices that need it.

If you don't know what to do here, say Y.