netfilter: nf_tables: Fix a memory leak in nf_tables_updchain

In the Linux kernel, the following vulnerability has been resolved: 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.