When kmemdup called failed and register_net_sysctl return NULL, should
return ENOMEM instead of ENOBUFS
Signed-off-by: liuguoqiang <liuguoqiang@uniontech.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>