Get rid of the last usage of the locked mv88e6xxx_reg_read function with
a new mv88e6xxx_port_read helper, useful later for chips with different
port registers base address.
Signed-off-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>