scsi: fix host max depth checking for the 'queue_depth' sysfs interface

Commit 1e6f241 changed the scsi sysfs 'queue_depth' code to
rejects depths higher than the scsi host template setting. But lots
of hosts set this to 1, and update the settings in the scsi host
when the controller/devices probing happens.

This breaks (at least) mpt2sas and mpt3sas runtime setting of queue
depth, returning EINVAL for all settings but '1'. And once it's set to
1, there's no way to go back up.

Cc: [email protected]
Fixes: 1e6f241 "scsi: don't allow setting of queue_depth bigger than can_queue"
Signed-off-by: Jens Axboe <[email protected]>
Reviewed-by: Martin K. Petersen <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: James Bottomley <[email protected]>

drivers/scsi/scsi_sysfs.c

@@ -859,7 +859,7 @@ sdev_store_queue_depth(struct device *dev, struct device_attribute *attr,
 
 	depth = simple_strtoul(buf, NULL, 0);
 
-	if (depth < 1 || depth > sht->can_queue)
+	if (depth < 1 || depth > sdev->host->can_queue)
 		return -EINVAL;
 
 	retval = sht->change_queue_depth(sdev, depth);