net: mdio: Add workaround for Micrel PHYs which are not C45 compatible

After scanning the bus for C22 devices, check if any Micrel PHYs have
been found.  They are known to do bad things if there are C45
transactions on the bus. Prevent the scanning of the bus using C45 if
such a PHY has been detected.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>