[SCSI] fcoe: fip: add multicast filter to receive FIP advertisements.

The FCoE forwarder (FCF) would be selected, but then would soon time
out after three advertisements were missed.  This would be 24 seconds
by default, or 3 times the keep-alive interval configured on the switch.

The cause was that the multicast address for all FIP E-nodes
was never added.

Signed-off-by: Joe Eykholt <jeykholt@cisco.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>