CONFIG_MIPS_MT is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_MIPS_MT (not configurable)

modulename: mips-mt.ko

configname: CONFIG_MIPS_MT

Linux Kernel Configuration
└─>Kernel type
└─>MIPS_MT
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
source code:
arch/mips/kernel/mips-mt.c
is depended by
CONFIG_MIPS_MT_SMP