[SCSI] scsi_queue_work() documented return value is incorrect

If you examine the queue_work() routine you'll see that it returns
1 on success, 0 if the work is already queued.

This patch corrects the source code documentation for the
scsi_queue_work function.
Signed-off-by: Michael Reed <mdr@sgi.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/hosts.c

@@ -487,7 +487,9 @@ EXPORT_SYMBOL(scsi_is_host_device);
  * @work:	Work to queue for execution.
  *
  * Return value:
- * 	0 on success / != 0 for error
+ * 	1 - work queued for execution
+ *	0 - work is already queued
+ *	-EINVAL - work queue doesn't exist
  **/
 int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
 {