scsi: don't set tagging state from scsi_adjust_queue_depth

Remove the tagged argument from scsi_adjust_queue_depth, and just let it
handle the queue depth.  For most drivers those two are fairly separate,
given that most modern drivers don't care about the SCSI "tagged" status
of a command at all, and many old drivers allow queuing of multiple
untagged commands in the driver.

Instead we start out with the ->simple_tags flag set before calling
->slave_configure, which is how all drivers actually looking at
->simple_tags except for one worke anyway.  The one other case looks
broken, but I've kept the behavior as-is for now.

Except for that we only change ->simple_tags from the ->change_queue_type,
and when rejecting a tag message in a single driver, so keeping this
churn out of scsi_adjust_queue_depth is a clear win.

Now that the usage of scsi_adjust_queue_depth is more obvious we can
also remove all the trivial instances in ->slave_alloc or ->slave_configure
that just set it to the cmd_per_lun default.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/libiscsi.c

@@ -1775,13 +1775,13 @@ int iscsi_change_queue_depth(struct scsi_device *sdev, int depth, int reason)
 {
 	switch (reason) {
 	case SCSI_QDEPTH_DEFAULT:
-		scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
+		scsi_adjust_queue_depth(sdev, depth);
 		break;
 	case SCSI_QDEPTH_QFULL:
 		scsi_track_queue_full(sdev, depth);
 		break;
 	case SCSI_QDEPTH_RAMP_UP:
-		scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
+		scsi_adjust_queue_depth(sdev, depth);
 		break;
 	default:
 		return -EOPNOTSUPP;