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/onenand/onenand_sim.c b/drivers/mtd/onenand/onenand_sim.c
index 5ef3bd5..85399e3 100644
--- a/drivers/mtd/onenand/onenand_sim.c
+++ b/drivers/mtd/onenand/onenand_sim.c
@@ -539,7 +539,8 @@
 		return -ENXIO;
 	}
 
-	add_mtd_partitions(&info->mtd, info->parts, ARRAY_SIZE(os_partitions));
+	mtd_device_register(&info->mtd, info->parts,
+			    ARRAY_SIZE(os_partitions));
 
 	return 0;
 }