netfilter: nf_tables: report EOPNOTSUPP on unsupported flags/object type

commit d9583cdf2f38d0f526d9a8c8564dd2e35e649bc7 upstream.

EINVAL should be used for malformed netlink messages. New userspace
utility and old kernels might easily result in EINVAL when exercising
new set features, which is misleading.

Fixes: 8aeff920 ("netfilter: nf_tables: add stateful object reference to set elements")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>