Merge branch 'mlxsw-Add-support-for-400Gbps-50Gbps-per-lane-link-modes'

Jiri Pirko says:

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mlxsw: Add support for 400Gbps (50Gbps per lane) link modes

Add 400Gbps bits to ethtool and introduce support in mlxsw. These modes
are supported by the Spectrum-2 switch ASIC.
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Signed-off-by: David S. Miller <davem@davemloft.net>