bnx2x: Moved enabling of MSI to the bnx2x_set_num_queues()

Moved enabling of MSI to the bnx2x_set_num_queues() - the same functions that
 handles the initialization of the MSI-X.

From: Vladislav Zolotarov <vladz@broadcom.com>
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>