CONFIG_CPU_MIPS64 is not available for the selected architecture x86.
Result is shown for architecture mips

MIPS64

modulename: r4k_fpu.ko

and/or

c-r4k.ko

and/or

dump_tlb.ko

configname: CONFIG_CPU_MIPS64

CPU type
└─>MIPS64
In linux kernel since version 2.6.12 )
source code:
arch/mips/mm/