default or selected kernelversion does not have config value CONFIG_ARM_EXYNOS4_BUS_DEVFREQ.
Result is shown for kernelversion 5.9.8

ARM Exynos4210/4212/4412 Memory Bus DEVFREQ Driver

modulename: exynos_ppmu.ko

Linux Kernel Configuration
└─> Device Drivers
└─> Generic Dynamic Voltage and Frequency Scaling (DVFS) support
└─> ARM Exynos4210/4212/4412 Memory Bus DEVFREQ Driver

This adds the DEVFREQ driver for Exynos4210 memory bus (vdd_int)
and Exynos4212/4412 memory interface and bus (vdd_mif + vdd_int).
It reads PPMU counters of memory controllers and adjusts
the operating frequencies and voltages with OPP support.
This does not yet operate with optimal voltages.

source code: