[SCSI] Fix command result state propagation

We're seeing a case where the contents of scmd->result isn't being reset after
a SCSI command encounters an error, is resubmitted, times out and then gets
handled.  The error handler acts on the stale result of the previous error
instead of the timeout.  Fix this by properly zeroing the scmd->status before
the command is resubmitted.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/scsi_lib.c

@@ -137,6 +137,7 @@ static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
 	 * lock such that the kblockd_schedule_work() call happens
 	 * before blk_cleanup_queue() finishes.
 	 */
+	cmd->result = 0;
 	spin_lock_irqsave(q->queue_lock, flags);
 	blk_requeue_request(q, cmd->request);
 	kblockd_schedule_work(q, &device->requeue_work);