default or selected kernelversion does not have config value CONFIG_RTC_DRV_BFIN.
Result is shown for kernelversion 6.7-rc3

Blackfin On-Chip RTC

modulename: rtc-bfin.ko


Linux Kernel Configuration
└─>Device Drivers
└─>Real Time Clock
└─>Blackfin On-Chip RTC
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
If you say yes here you will get support for the
Blackfin On-Chip Real Time Clock.

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

source code: