net: dsa: mv88e6xxx: fix setup of port control 1

mv88e6xxx_setup_port_common was writing to PORT_DEFAULT_VLAN (port
offset 0x07) instead of PORT_CONTROL_1 (port offset 0x05).

Fixes: cca8b133

 ("net: dsa: Use mnemonics rather than register numbers")
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Acked-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>