mainline inclusion
from mainline-v5.1
commit c93ad133
category: bugfix
bugzilla: 13690
CVE: CVE-2019-19227

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

If register_snap_client fails in atalk_init,
error code should be set, otherwise it will
triggers NULL pointer dereference while unloading
module.

Fixes: 9804501f ("appletalk: Fix potential NULL pointer dereference in unregister_snap_client")
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NYue Haibing <yuehaibing@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>