net: dsa: mv88e6xxx: Implement mv88e6390 pause control

The mv88e6390 has a number flow control registers accessed via the
Flow Control register. Use these to set the pause control.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/port.h

@@ -66,5 +66,6 @@ int mv88e6165_port_jumbo_config(struct mv88e6xxx_chip *chip, int port);
 int mv88e6095_port_egress_rate_limiting(struct mv88e6xxx_chip *chip, int port);
 int mv88e6097_port_egress_rate_limiting(struct mv88e6xxx_chip *chip, int port);
 int mv88e6097_port_pause_config(struct mv88e6xxx_chip *chip, int port);
+int mv88e6390_port_pause_config(struct mv88e6xxx_chip *chip, int port);
 
 #endif /* _MV88E6XXX_PORT_H */