net: lan743x: Migrate phylib to phylink

Migrate phy support from phylib to phylink.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>