MV88E6XXX_FAMILY_6321 is undefined, 88E6321's family is 88E6320,
fix this.
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>