default or selected kernelversion does not have config value CONFIG_REGULATOR_BD71837.
Result is shown for kernelversion 5.10.188

ROHM BD71837 Power Regulator

modulename: bd71837-regulator.ko

configname: CONFIG_REGULATOR_BD71837

Linux Kernel Configuration
└─>Device Drivers
└─>Voltage and Current Regulator Support
└─>ROHM BD71837 Power Regulator
In linux kernel since version 4.18 (release Date: 2018-08-12)  
This driver supports voltage regulators on ROHM BD71837 PMIC.
This will enable support for the software controllable buck
and LDO regulators.

This driver can also be built as a module. If so, the module
will be called bd71837-regulator.

source code: