netfilter: nf_tables: Fix a memory leak in nf_tables_updchain
If nft_netdev_register_hooks() fails, the memory associated with
nft_stats is not freed, causing a memory leak.
This patch fixes it by moving nft_stats_alloc() down after
nft_netdev_register_hooks() succeeds.
Fixes: b9703ed44ffb ("netfilter: nf_tables: support for adding new devices to an existing netdev chain") Signed-off-by: Quan Tian <tianquan23@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>