Revert "Support EVP_PKEY_sign() and EVP_PKEY_verify() for EdDSA"

This reverts commit a6f5b1163452a36da1c8378eab3f29ae234e5c7f.

The EVP_PKEY_sign() function is intended for pre-hashed input which is
not supported by our EdDSA implementation.

See the discussion in PR 5880

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6284)
4 files changed