mtd: name the mtd device with an optional label property

This can be used to easily identify a specific chip on a system with
multiple chips.
Suggested-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: NCédric Le Goater <clg@kaod.org>
Reviewed-by: NMarek Vasut <marek.vasut@gmail.com>
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>

include/linux/mtd/mtd.h

@@ -24,6 +24,7 @@
 #include <linux/uio.h>
 #include <linux/notifier.h>
 #include <linux/device.h>
+#include <linux/of.h>
 
 #include <mtd/mtd-abi.h>
 
@@ -386,6 +387,8 @@ static inline void mtd_set_of_node(struct mtd_info *mtd,
 				   struct device_node *np)
 {
 	mtd->dev.of_node = np;
+	if (!mtd->name)
+		of_property_read_string(np, "label", &mtd->name);
 }
 
 static inline struct device_node *mtd_get_of_node(struct mtd_info *mtd)