GOST MAC algorithms don't support EVP_PKEY_new_raw_private_key()

We should use the old EVP_PKEY_new_mac_key() instead.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5808)