bnx2x: handle iSCSI SD mode

in iSCSI SD mode to bnx2x device assigned single mac address
which is supposted to be iscsi mac. If this mode is recognized
bnx2x will disable LRO, decrease number of queues to 1 and rx ring
size to the minumum allowed by FW, this in order minimize memory use.
It will tranfer mac for iscsi usage and zero primary mac of the netdev.

Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Reviewed-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>