[SCSI] iscsi regression: check for zero max session cmds

The old tools did not set max session cmds. This is a regression.
I removed the check when merging the power of 2 patch.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 59f8445..bdd7de7 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -1708,8 +1708,8 @@
 		qdepth = ISCSI_DEF_CMD_PER_LUN;
 	}
 
-	if (!is_power_of_2(cmds_max) ||
-	    cmds_max >= ISCSI_MGMT_ITT_OFFSET) {
+	if (!is_power_of_2(cmds_max) || cmds_max >= ISCSI_MGMT_ITT_OFFSET ||
+	    cmds_max < 2) {
 		if (cmds_max != 0)
 			printk(KERN_ERR "iscsi: invalid can_queue of %d. "
 			       "can_queue must be a power of 2 and between "