default or selected kernelversion does not have config value CONFIG_ISDN_DRV_PCBIT.
Result is shown for kernelversion 6.5.1

PCBIT-D support

modulename: pcbit.ko

configname: CONFIG_ISDN_DRV_PCBIT

Linux Kernel Configuration
└─>Device Drivers
└─>ISDN support
└─>Old ISDN4Linux (deprecated)
└─>Active cards
└─>PCBIT-D support
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
This enables support for the PCBIT ISDN-card. This card is
manufactured in Portugal by Octal. For running this card,
additional firmware is necessary, which has to be downloaded into
the card using a utility which is distributed separately. See
Documentation/isdn/README and
Documentation/isdn/README.pcbit for more information.

source code:
depends
CONFIG_ISA
CONFIG_ISDN
CONFIG_ISDN_I4L
CONFIG_BROKEN or CONFIG_X86