mtd: fix repeated word in comment

Delete the redundant word 'in'.
Signed-off-by: wangjianli <wangjianli@cdjrlc.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220908122229.10814-1-wangjianli@cdjrlc.com

drivers/mtd/mtdconcat.c

@@ -836,7 +836,7 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],	/* subdevices to c
 
 		/*
 		 * walk the map of the new device once more and fill in
-		 * in erase region info:
+		 * erase region info:
 		 */
 		curr_erasesize = subdev[0]->erasesize;
 		begin = position = 0;