IB/mlx5: Add support for 400G_8X lane speed

IB/mlx5: Add support for 400G_8X lane speed

Currently, when driver queries PTYS to report which link speed is being
used on its RoCE ports, it does not check the case of having 400Gbps
transmitted over 8 lanes. Thus it fails to report the said speed and
instead it defaults to report 10G over 4 lanes.

Add a check for the said speed when querying PTYS and report it back
correctly when needed.

Fixes: 08e8676f1607 ("IB/mlx5: Add support for 50Gbps per lane link modes")
Signed-off-by: Maher Sanalla <msanalla@nvidia.com>
Reviewed-by: Aya Levin <ayal@nvidia.com>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Link: https://lore.kernel.org/r/ec9040548d119d22557d6a4b4070d6f421701fd4.1678973994.git.leon@kernel.org
Signed-off-by: Leon Romanovsky <leon@kernel.org>