'mbedtls_pk_psa_rsa_sign_ext' function allocates a buffer of maximum
size 5679 bytes (MBEDTLS_PK_RSA_PRV_DER_MAX_BYTES) on the stack to store
DER encoded private key. This increased stack usage significantly for
RSA signature operations when MBEDTLS_PSA_CRYPTO_C is defined.
This issue was discovered when adding support for EAP-TLS 1.3 (rfc9190).
Signed-off-by: Sarvesh Bodakhe <sarvesh.bodakhe@espressif.com>
