scsi: fcoe: separate out fcoe_vport_remove()

Separate out fcoe_vport_remove() from fcoe_destroy_work().  Required for
the next patch.

Signed-off-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Lee Duncan <lduncan@suse.com>
Acked-by: Johannes Thumshirn <jth@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>