SERIALIZER: No enc argument for OSSL_SERIALIZER_CTX_set_passphrase_cb()

SERIALIZER: No enc argument for OSSL_SERIALIZER_CTX_set_passphrase_cb()

Serialization will only encrypt, so there's no point telling
OSSL_SERIALIZER_CTX_set_passphrase_cb() that's going to happen.

We fix the declaration of OSSL_DESERIALIZER_CTX_set_passphrase_cb()
the same way.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/12410)