Run DH_check_ex() not DH_check_params_ex() when checking params

Run DH_check_ex() not DH_check_params_ex() when checking params

Both DH_check_ex() and DH_check_params_ex() check the parameters.
DH_check_ex() performs a more complete check, while DH_check_params_ex()
performs a lightweight check. In 1.1.1 EVP_PKEY_param_check() would call
DH_check_ex() for DH keys. For backwards compatibility we should continue
with that behaviour.

Fixes #13501

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/14146)