[SCSI] fcoe: move the host-list add/remove to keep out VN_Ports

We only want the FCoE create and destroy routines to deal with top level
N_Ports, the VN_Ports are tracked on the vport list (see scsi_transport_fc).

Signed-off-by: Chris Leech <christopher.leech@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>