CONFIG_LITEX (not configurable)

configname: CONFIG_LITEX

Linux Kernel Configuration
└─>Device Drivers
└─>SOC (System On Chip) specific Drivers
└─>Enable LiteX SoC Builder specific drivers
└─>LITEX
In linux kernel since version 5.2 (release Date: 2019-07-07)  
is selected by
CONFIG_SERIAL_LITEUART