[SCSI] fix q->lock not held warning when target is busy

We cannot call blk_plug_device from scsi_target_queue_ready
because the q lock is not held. And we do not need to call
it from there because when we return 0, the scsi_request_fn
not_ready handling will plug the queue for us if needed.
Signed-off-by: NMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/scsi_lib.c

@@ -1291,10 +1291,8 @@ static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
 		if (--starget->target_blocked == 0) {
 			SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
 					 "unblocking target at zero depth\n"));
-		} else {
-			blk_plug_device(sdev->request_queue);
+		} else
 			return 0;
-		}
 	}
 
 	if (scsi_target_is_busy(starget)) {