CONFIG_NO_MMU is not available for thedefaultarchitecture x86.
Result is shown for architecture microblaze
default or selected kernelversion does not have config value CONFIG_NO_MMU.
Result is shown for kernelversion 6.2.5

CONFIG_NO_MMU (not configurable)

configname: CONFIG_NO_MMU

Linux Kernel Configuration
└─>Processor type and features
└─>NO_MMU
In linux kernel since version 2.6.30 (release Date: 2009-06-09)  
depends
NOT CONFIG_MMU