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

Blackfin on-chip MAC support

modulename: bfin_mac.ko

configname: CONFIG_BFIN_MAC

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>Ethernet driver support
└─>Blackfin on-chip MAC support
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
This is the driver for Blackfin on-chip mac device. Say Y if you want
it compiled into the kernel. This driver is also available as a
module ( = code which can be inserted in and removed from the running
kernel whenever you want). The module will be called bfin_mac.

source code: