bnx2x: Clear fip MAC when fcoe offload support is disabled

On some customer setups it was observed that shmem contains a non-zero fip
MAC for 57711 which would lead to enabling of SW FCoE.
Add a software workaround to clear the bad fip mac address if no FCoE
connections are supported.

Signed-off-by: Sudarsana Reddy Kalluru <Sudarsana.Kalluru@cavium.com>
Signed-off-by: Ariel Elior <ariel.elior@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>