default or selected kernelversion does not have config value CONFIG_ATH6KL_ENABLE_COEXISTENCE.
Result is shown for kernelversion 6.2.5

BT Coexistence support

configname: CONFIG_ATH6KL_ENABLE_COEXISTENCE

Linux Kernel Configuration
└─>Device Drivers
└─>Staging drivers
└─>BT Coexistence support
In linux kernel since version 2.6.37 (release Date: 2011-01-04)  
Enables WLAN/BT coexistence support. Select the apprpriate configuration from below.