default or selected kernelversion does not have config value CONFIG_REGULATOR_AB3100.
Result is shown for kernelversion 6.8.2

ST-Ericsson AB3100 Regulator functions

modulename: regulator.ko

and/or

ab3100.ko

configname: CONFIG_REGULATOR_AB3100

Linux Kernel Configuration
└─>Device Drivers
└─>Voltage and Current Regulator Support
└─>ST-Ericsson AB3100 Regulator functions
In linux kernel since version 2.6.32 (release Date: 2009-12-02)  
These regulators correspond to functionality in the
AB3100 analog baseband dealing with power regulators
for the system.

source code: