Factor out common code from the tag_ksz , so that the code can be used
with other KSZ family switches which use differenly sized tags.
Signed-off-by: Tristram Ha <Tristram.Ha@microchip.com> Signed-off-by: Marek Vasut <marex@denx.de> Cc: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Cc: Woojung Huh <woojung.huh@microchip.com> Cc: David S. Miller <davem@davemloft.net> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: David S. Miller <davem@davemloft.net>