netfilter: nf_tables: don't unregister hook when table is dormant

netfilter: nf_tables: don't unregister hook when table is dormant

[ Upstream commit 688c15017d5cd5aac882400782e7213d40dc3556 ]

When nf_tables_updchain encounters an error, hook registration needs to
be rolled back.

This should only be done if the hook has been registered, which won't
happen when the table is flagged as dormant (inactive).

Just move the assignment into the registration block.

Reported-by: syzbot+53ed3a6440173ddbf499@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=53ed3a6440173ddbf499
Fixes: b9703ed44ffb ("netfilter: nf_tables: support for adding new devices to an existing netdev chain")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>