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

Deadline I/O scheduler

modulename: deadline-iosched.ko

configname: CONFIG_IOSCHED_DEADLINE

Linux Kernel Configuration
└─>Enable the block layer
└─>IO Schedulers
└─>Deadline I/O scheduler
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
The deadline I/O scheduler is simple and compact. It will provide
CSCAN service with FIFO expiration of requests, switching to
a new point in the service tree and doing a batch of IO from there
in case of expiry.

source code:
depends
CONFIG_BLOCK