net: dsa: mv88e6xxx: add egress mode enumeration

As for the frame mode, add a mv88e6xxx_egress_mode enumeration instead
of a 16-bit register mask.

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

drivers/net/dsa/mv88e6xxx/port.h

@@ -212,7 +212,7 @@ int mv88e6xxx_port_set_8021q_mode(struct mv88e6xxx_chip *chip, int port,
 int mv88e6095_port_tag_remap(struct mv88e6xxx_chip *chip, int port);
 int mv88e6390_port_tag_remap(struct mv88e6xxx_chip *chip, int port);
 int mv88e6xxx_port_set_egress_mode(struct mv88e6xxx_chip *chip, int port,
-				   u16 mode);
+				   enum mv88e6xxx_egress_mode mode);
 int mv88e6085_port_set_frame_mode(struct mv88e6xxx_chip *chip, int port,
 				  enum mv88e6xxx_frame_mode mode);
 int mv88e6351_port_set_frame_mode(struct mv88e6xxx_chip *chip, int port,