default or selected kernelversion does not have config value CONFIG_UART2_RTS_PIN.
Result is shown for kernelversion 5.4.69
UART2 RTS pin
configname: CONFIG_UART2_RTS_PIN
Linux Kernel Configuration
└─>Device Drivers
└─>Character devices
└─>Serial drivers
└─>UART2 RTS pin
In linux kernel since version 2.6.24 (release Date: 2008-01-24)
Refer to arch/blackfin/mach-*/include/mach/gpio.h to see the GPIO map.