default or selected kernelversion does not have config value CONFIG_SDLA.
Result is shown for kernelversion 6.9.9

SDLA (Sangoma S502/S508) support

modulename: sdla.ko

configname: CONFIG_SDLA

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>Wan interfaces support
└─>SDLA (Sangoma S502/S508) support
In linux kernel since version 2.6.12  
Driver for the Sangoma S502A, S502E, and S508 Frame Relay Access
Devices.

These are multi-protocol cards, but only Frame Relay is supported
by the driver at this time. Please read
<file:Documentation/networking/framerelay.txt>.

To compile this driver as a module, choose M here: the
module will be called sdla.

source code: