Merge branch 'net-phy-XLGMII-define-and-usage-in-PHYLINK'

Jose Abreu says:

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net: phy: XLGMII define and usage in PHYLINK

Adds XLGMII defines and usage in PHYLINK.

Patch 1/2, adds the define for it, whilst 2/2 adds the usage of it in
PHYLINK.
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Signed-off-by: David S. Miller <davem@davemloft.net>