CONFIG_CPU_J2 is not available for thedefaultarchitecture x86.
Result is shown for architecture sh

CONFIG_CPU_J2 (not configurable)

configname: CONFIG_CPU_J2

Linux Kernel Configuration
└─>System type
└─>CPU_J2
In linux kernel since version 4.1 (release Date: 2015-06-21)  

is selected by
CONFIG_SH_JCORE_SOC