Revert "rtnetlink: Reject negative ifindexes in RTM_NEWLINK"

stable inclusion
from stable-v4.19.296
commit 88f8a01c42535285bcf2666d1f7eb9ada0de88cc
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8XA2F


CVE: NA

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

This reverts commit 42c8406432e730cb7442d97ecfdbf47084a5af4d which is
commit 30188bd7 upstream.

It was improperly backported to 4.19.y, and applied to the wrong
function, which obviously causes problems.  A fixed version will be
applied as a separate commit later.

Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/ZSQeA8fhUT++iZvz@ostr-mac


Cc: Ido Schimmel <idosch@nvidia.com>
Cc: Jiri Pirko <jiri@nvidia.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Wang Yufen <wangyufen@huawei.com>