As of mv88e6xxx remove the poll_link callback since the link
state change polling is now handled by the phylib.
Tested on a mv88e6060 B0 device with a TI DM816X SoC.
Suggested-by: Andrew Lunn <andrew@lunn.ch> Acked-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com> Signed-off-by: David S. Miller <davem@davemloft.net>