default or selected kernelversion does not have config value CONFIG_BFIN_SIR3.
Result is shown for kernelversion 6.7-rc3

Blackfin SIR on UART3

configname: CONFIG_BFIN_SIR3

Linux Kernel Configuration
└─>Device Drivers
└─>Staging drivers
└─>IrDA (infrared) subsystem support
└─>Infrared-port device drivers
└─>Blackfin SIR on UART3
In linux kernel since version 2.6.31 (release Date: 2009-09-09)