[PATCH] class_simple cleanup in sg

The only spot that seems to care about class_simple_device_add possibly
failing, but it gets the wrong error test.

drivers/scsi/sg.c

@@ -1439,7 +1439,7 @@ sg_add(struct class_device *cl_dev)
 				MKDEV(SCSI_GENERIC_MAJOR, k), 
 				cl_dev->dev, "%s", 
 				disk->disk_name);
-		if (NULL == sg_class_member)
+		if (IS_ERR(sg_class_member))
 			printk(KERN_WARNING "sg_add: "
 				"class_simple_device_add failed\n");
 		class_set_devdata(sg_class_member, sdp);