net: dsa: mv88e6xxx: Refactor remaining port setup

Move the remaining port configuration code which varies per device
into port.c, using ops were necessary. This makes
mv88e6xxx_6185_family() and mv88e6xxx_6095_family() unused, so remove
them.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>