default or selected kernelversion does not have config value CONFIG_ASYMMETRIC_TPM_KEY_SUBTYPE.
Result is shown for kernelversion 6.9.2

Asymmetric TPM backed private key subtype

modulename: asym_tpm.ko


Linux Kernel Configuration
└─>Cryptographic API
└─>Asymmetric (public-key cryptographic) key type
└─>Asymmetric TPM backed private key subtype
In linux kernel since version 4.2 (release Date: 2015-08-30)  
This option provides support for TPM backed private key type handling.
Operations such as sign, verify, encrypt, decrypt are performed by
the TPM after the private key is loaded.

source code: