mtd: add get/set of_node/flash_node helpers

We are going to begin using the mtd->dev.of_node field for MTD device
nodes, so let's add helpers for it. Also, we'll be making some
conversions on spi_nor (and nand_chip eventually) too, so get that ready
with their own helpers.

Signed-off-by: Brian Norris <[e-mail]>
Reviewed-by: Boris Brezillon <[e-mail]>

include/linux/mtd/mtd.h

···
 	int usecount;
 };
 
+static inline void mtd_set_of_node(struct mtd_info *mtd,
+				   struct device_node *np)
+{
+	mtd->dev.of_node = np;
+}
+
+static inline struct device_node *mtd_get_of_node(struct mtd_info *mtd)
+{
+	return mtd->dev.of_node;
+}
+
 int mtd_erase(struct mtd_info *mtd, struct erase_info *instr);
 int mtd_point(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
 	      void **virt, resource_size_t *phys);

include/linux/mtd/nand.h

···
 	void *priv;
 };
 
+static inline void nand_set_flash_node(struct nand_chip *chip,
+				       struct device_node *np)
+{
+	chip->flash_node = np;
+}
+
+static inline struct device_node *nand_get_flash_node(struct nand_chip *chip)
+{
+	return chip->flash_node;
+}
+
 /*
  * NAND Flash Manufacturer ID Codes
  */

include/linux/mtd/spi-nor.h

···
 	void *priv;
 };
 
+static inline void spi_nor_set_flash_node(struct spi_nor *nor,
+					  struct device_node *np)
+{
+	nor->flash_node = np;
+}
+
+static inline struct device_node *spi_nor_get_flash_node(struct spi_nor *nor)
+{
+	return nor->flash_node;
+}
+
 /**
  * spi_nor_scan() - scan the SPI NOR
  * @nor:	the spi_nor structure