mtd: rawnand: Remove forward declaration of device_node

struct device_node is defined in linux/of.h. Let's include this file
instead of having a forward declaration of this struct.
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

include/linux/mtd/rawnand.h

@@ -21,10 +21,10 @@
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/flashchip.h>
 #include <linux/mtd/bbm.h>
+#include <linux/of.h>
 #include <linux/types.h>
 
 struct nand_flash_dev;
-struct device_node;
 
 /* Scan and identify a NAND device */
 int nand_scan_with_ids(struct mtd_info *mtd, int max_chips,