mtd: call the remove notifiers before assuming it is in use

Now that mtd block common layer is prepared for proper hotplug support,
enable it here

Now all users of the mtd device have a chance to put the mtd device
when they are notified to do so, and they have to do so to make hotplug work.

[dwmw2: There's more work to be done to fix hotplug in the general case, but
        this is a reasonable start]
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/mtdcore.c

@@ -350,31 +350,34 @@ int add_mtd_device(struct mtd_info *mtd)
 int del_mtd_device (struct mtd_info *mtd)
 {
 	int ret;
+	struct mtd_notifier *not;
 
 	mutex_lock(&mtd_table_mutex);
 
 	if (idr_find(&mtd_idr, mtd->index) != mtd) {
 		ret = -ENODEV;
-	} else if (mtd->usecount) {
-		printk(KERN_NOTICE "Removing MTD device #%d (%s) with use count %d\n",
-		       mtd->index, mtd->name, mtd->usecount);
-		ret = -EBUSY;
-	} else {
-		struct mtd_notifier *not;
-
-		device_unregister(&mtd->dev);
+		goto out_error;
+	}
 
 	/* No need to get a refcount on the module containing
 		the notifier, since we hold the mtd_table_mutex */
 	list_for_each_entry(not, &mtd_notifiers, list)
 		not->remove(mtd);
 
+	if (mtd->usecount) {
+		printk(KERN_NOTICE "Removing MTD device #%d (%s) with use count %d\n",
+		       mtd->index, mtd->name, mtd->usecount);
+		ret = -EBUSY;
+	} else {
+		device_unregister(&mtd->dev);
+
 		idr_remove(&mtd_idr, mtd->index);
 
 		module_put(THIS_MODULE);
 		ret = 0;
 	}
 
+out_error:
 	mutex_unlock(&mtd_table_mutex);
 	return ret;
 }