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

CONFIG_MIPS_ASID_BITS_VARIABLE (not configurable)

configname: CONFIG_MIPS_ASID_BITS_VARIABLE

Linux Kernel Configuration
└─>Kernel type
└─>MIPS_ASID_BITS_VARIABLE
In linux kernel since version 3.10 (release Date: 2013-06-30)  
is depended by
CONFIG_CPU_LOONGSON64