IB/mlx5: Rename 400G_8X speed to comply to naming convention

IB/mlx5: Rename 400G_8X speed to comply to naming convention

[ Upstream commit b28ad32442bec2f0d9cb660d7d698a1a53c13d08 ]

Rename 400G_8X speed to comply to naming convention.

Signed-off-by: Patrisious Haddad <phaddad@nvidia.com>
Reviewed-by: Mark Zhang <markzhang@nvidia.com>
Link: https://lore.kernel.org/r/ac98447cac8379a43fbdb36d56e5fb2b741a97ff.1695204156.git.leon@kernel.org
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Stable-dep-of: 80bf474242b2 ("net/mlx5e: Add missing link mode to ptys2ext_ethtool_map")
Signed-off-by: Sasha Levin <sashal@kernel.org>