net/mlx5: devcom only supports 2 ports

stable inclusion
from stable-v5.10.182
commit 57dc3c124e7bf2b937086e4b57c4a834b02c0457
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8GJZJ

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=57dc3c124e7bf2b937086e4b57c4a834b02c0457



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

[ Upstream commit 8a6e75e5 ]

Devcom API is intended to be used between 2 devices only add this
implied assumption into the code and check when it's no true.

Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Stable-dep-of: 1f893f57 ("net/mlx5: Devcom, serialize devcom registration")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>
(cherry picked from commit c5b937bf)