mtd: convert remaining users to mtd_device_register()

The older add_mtd_device()/add_mtd_partitions() and their removal
counterparts will soon be gone.  Replace uses with mtd_device_register()
and mtd_device_unregister().

Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/nand/au1550nd.c b/drivers/mtd/nand/au1550nd.c
index 3ffe05d..001545b 100644
--- a/drivers/mtd/nand/au1550nd.c
+++ b/drivers/mtd/nand/au1550nd.c
@@ -580,7 +580,8 @@
 	}
 
 	/* Register the partitions */
-	add_mtd_partitions(au1550_mtd, partition_info, ARRAY_SIZE(partition_info));
+	mtd_device_register(au1550_mtd, partition_info,
+			    ARRAY_SIZE(partition_info));
 
 	return 0;