CONFIG_PPC_MICROWATT is not available for the selected architecture x86.
Result is shown for architecture powerpc
Microwatt SoC platform
configname: CONFIG_PPC_MICROWATT
Linux Kernel Configuration
└─>Microwatt SoC platform
In linux kernel since version 4.14.326 (release Date: 2023-09-23)
This option enables support for FPGA-based Microwatt implementations.