CONFIG_CPU_CP15_MMU is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_CPU_CP15_MMU (not configurable)

configname: CONFIG_CPU_CP15_MMU

Linux Kernel Configuration
└─>CPU_CP15_MMU
In linux kernel since version 2.6.21 (release Date: 2007-04-25)  
Processor has the CP15 register, which has MMU related registers.