EVP: Limit the diverse key parameter functions to domain params only

EVP: Limit the diverse key parameter functions to domain params only

Provider KEYMGMT functions can handle domain parameters as well as
"other" parameters (the cofactor mode flag in ECC keys is one of
those).  The public EVP functions EVP_PKEY_copy_parameters(),
EVP_PKEY_missing_parameters(), EVP_PKEY_cmp_parameters() and
EVP_PKEY_cmp() tried to handle all parameters, but looking back at
EVP_PKEY_ASN1_METHOD code (especially crypto/ec/ec_ameth.c), it turns
out that they only need to concern themselves with domain parameters.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11375)