For reduce "if" condition, easy to read/understand the code,
optimize "if" condition in rx/tx processing.
Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com> Acked-by: Marc Kleine-Budde <mkl@pengutronix.de> Signed-off-by: David S. Miller <davem@davemloft.net>