scsi: drop reason argument from ->change_queue_depth

Drop the now unused reason argument from the ->change_queue_depth method.
Also add a return value to scsi_adjust_queue_depth, and rename it to
scsi_change_queue_depth now that it can be used as the default
->change_queue_depth implementation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Reviewed-by: Hannes Reinecke <hare@suse.de>
diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index a575d84..0b8af18 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -952,7 +952,7 @@
 	.module			= THIS_MODULE,
 	.name			= "iSCSI Initiator over TCP/IP",
 	.queuecommand           = iscsi_queuecommand,
-	.change_queue_depth	= iscsi_change_queue_depth,
+	.change_queue_depth	= scsi_change_queue_depth,
 	.can_queue		= ISCSI_DEF_XMIT_CMDS_MAX - 1,
 	.sg_tablesize		= 4096,
 	.max_sectors		= 0xFFFF,