mlxsw: spectrum_ethtool: Add support for 100Gb/s per lane link modes

The Spectrum-4 ASIC supports 100Gb/s per lane link modes, but the only
one currently supported by the driver is 800Gb/s over eight lanes.

Add support for 100Gb/s over one lane, 200Gb/s over two lanes and
400Gb/s over four lanes.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/1d77830f6abcc4f0d57a7f845e5a6d97a75a434b.1712667750.git.petrm@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>