CONFIG_CPU_BIG_ENDIAN is not available for thedefaultarchitecture x86.
Result is shown for architecture sh

Big Endian

configname: CONFIG_CPU_BIG_ENDIAN

Endianness selection
└─>Big Endian
In linux kernel since version 2.6.12  
depends
NOT CONFIG_CPU_SH5

is selected by
CONFIG_TYPEC_UCSI

is depended by
CONFIG_ARC_PLAT_EZNPS