[SCSI] iscsi: lower queue depth

From Wang Zhenyu:

High queue depth was a problem for some targets so make queue_depth adjustable

From Mike Christie

Make default queue_depth a little lower

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Alex Aizman <itn780@yahoo.com>
Signed-off-by: Dmitry Yusupov <dmitry_yus@yahoo.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/drivers/scsi/iscsi_tcp.h b/drivers/scsi/iscsi_tcp.h
index d23ae68..855f2df 100644
--- a/drivers/scsi/iscsi_tcp.h
+++ b/drivers/scsi/iscsi_tcp.h
@@ -71,7 +71,8 @@
 #define ISCSI_MGMT_CMDS_MAX		32	/* must be power of 2 */
 #define ISCSI_MGMT_ITT_OFFSET		0xa00
 #define ISCSI_SG_TABLESIZE		SG_ALL
-#define ISCSI_CMD_PER_LUN		128
+#define ISCSI_DEF_CMD_PER_LUN		32
+#define ISCSI_MAX_CMD_PER_LUN		128
 #define ISCSI_TCP_MAX_CMD_LEN		16
 
 #define ITT_MASK			(0xfff)