bnx2x: Duplication in promisc mode

Prevent packets duplication for frames targeting FCoE L2 ring:
packets were arriving to stack from both L2 RSS and from FCoE
L2 in a promiscuous mode.

Configure FCoE L2 ring to DROP_ALL rx mode, when interface is
configured to PROMISC, and to accept only unicast frames, when
interface is configured to ALL_MULTI.

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>