net: dsa: mv88e6xxx: Move switch product IDs into common include file

This will let us use the switch product IDs in the common source code.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>