Merge branch 'phy_check_downshift'

Heiner Kallweit says:

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net: phy: add and use phy_check_downshift

So far PHY drivers have to check whether a downshift occurred to be
able to notify the user. To make life of drivers authors a little bit
easier move the downshift notification to phylib. phy_check_downshift()
compares the highest mutually advertised speed with the actual value
of phydev->speed (typically read by the PHY driver from a
vendor-specific register) to detect a downshift.

v2: Add downshift hint to phy_print_status().
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Signed-off-by: David S. Miller <davem@davemloft.net>