[SCSI] add commands at the tail of cmd_list

It's probably going to be a fifo, so it should be more efficient
for taking them off again

drivers/scsi/scsi.c

@@ -412,7 +412,7 @@ struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, int gfp_mask)
 		init_timer(&cmd->eh_timeout);
 		INIT_LIST_HEAD(&cmd->list);
 		spin_lock_irqsave(&dev->list_lock, flags);
-		list_add(&dev->cmd_list, &cmd->list);
+		list_add_tail(&cmd->list, &dev->cmd_list);
 		spin_unlock_irqrestore(&dev->list_lock, flags);
 	}