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

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

commit 1278dd6809b11dc298e19d81ac0916275f7318c1 upstream.

Commit 1e6f2416044c0 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.

Fixes: 1e6f2416044c0 "scsi: don't allow setting of queue_depth bigger than can_queue"
Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>