net: caif: add proper error handling

stable inclusion
from stable-v4.19.194
commit 758f725c392ec073f9f1cfbe34323ca1372afbf8
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I990B2
CVE: CVE-2021-47121

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=758f725c392ec073f9f1cfbe34323ca1372afbf8



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

commit a2805dca upstream.

caif_enroll_dev() can fail in some cases. Ingnoring
these cases can lead to memory leak due to not assigning
link_support pointer to anywhere.

Fixes: 7c18d220 ("caif: Restructure how link caif link layer enroll")
Cc: stable@vger.kernel.org
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Liu Jian <liujian56@huawei.com>