mtd: nand: add nand_to_mtd() helper

Add a new helper to retrieve the MTD device attached to a NAND chip.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index d671057..b614ed2 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -737,6 +737,11 @@
 	return mtd->priv;
 }
 
+static inline struct mtd_info *nand_to_mtd(struct nand_chip *chip)
+{
+	return &chip->mtd;
+}
+
 /*
  * NAND Flash Manufacturer ID Codes
  */