default or selected kernelversion does not have config value CONFIG_SPI_EFM32.
Result is shown for kernelversion 6.8.2

EFM32 SPI controller

modulename: spi-efm32.ko

configname: CONFIG_SPI_EFM32

Linux Kernel Configuration
└─>Device Drivers
└─>SPI support
└─>Device Tree and Open Firmware support
└─>EFM32 SPI controller
In linux kernel since version 3.12 (release Date: 2013-11-03)  
Driver for the spi controller found on Energy Micro's EFM32 SoCs.

source code: