bnx2x: Optimized the branching in the bnx2x_rx_int()

Optimized the branching in the bnx2x_rx_int() based on the fact
that FP CQE will always have at least one of START or STOP flags set,
so if not both bits are set and START bit is not set,
then it's a STOP bit that is set.

Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Vladislav Zolotarov <vladz@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>