mtd: rawnand: Remove forward declaration of mtd_info

struct mtd_info is defined in linux/mtd/mtd.h which is included
at the beginning of nand_base.c, there's thus no need for the
forward declaration of mtd_info.
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

include/linux/mtd/rawnand.h

@@ -23,7 +23,6 @@
 #include <linux/mtd/bbm.h>
 #include <linux/types.h>
 
-struct mtd_info;
 struct nand_flash_dev;
 struct device_node;