net/mlx5: Use RMW accessors for changing LNKCTL

net/mlx5: Use RMW accessors for changing LNKCTL

[ Upstream commit 30de872537bda526664d7a20b646adfb3e7ce6e6 ]

Don't assume that only the driver would be accessing LNKCTL of the upstream
bridge. ASPM policy changes can trigger write to LNKCTL outside of driver's
control.

Use RMW capability accessors which do proper locking to avoid losing
concurrent updates to the register value.

Suggested-by: Lukas Wunner <lukas@wunner.de>
Fixes: eabe8e5e88f5 ("net/mlx5: Handle sync reset now event")
Link: https://lore.kernel.org/r/20230717120503.15276-8-ilpo.jarvinen@linux.intel.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>