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

Max DLCI per device

configname: CONFIG_DLCI_MAX

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>Wan interfaces support
└─>Max DLCI per device
In linux kernel since version 2.6.12  
How many logical point-to-point frame relay connections (the
identifiers of which are called DCLIs) should be handled by each
of your hardware frame relay access devices.

Go with the default.