default or selected kernelversion does not have config value CONFIG_ARM_TSTEE.
Result is shown for kernelversion 6.10-rc4

Arm Trusted Services TEE driver

modulename: arm-tstee.ko

configname: CONFIG_ARM_TSTEE

Linux Kernel Configuration
└─>Device Drivers
└─>Trusted Execution Environment support
└─>Arm Trusted Services TEE driver
The Trusted Services project provides a framework for developing and
deploying device Root of Trust services in FF-A Secure Partitions.
This driver provides an interface to make Trusted Services Secure
Partitions accessible for user space clients, since the FF-A driver
doesn't implement a user space interface directly.

source code: