netfilter: nf_nat: Fix memleak in nf_nat_init

stable inclusion
from stable-5.10.9
commit 88a5c90f39b0f8f4a747f24bb68d8b22d558daa7
bugzilla: 47457

--------------------------------

commit 869f4fda upstream.

When register_pernet_subsys() fails, nf_nat_bysource
should be freed just like when nf_ct_extend_register()
fails.

Fixes: 1cd472bf ("netfilter: nf_nat: add nat hook register functions to nf_nat")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>