[MTD][NAND] au1550nd: remove unused variable

Remove unused variable from au1550 NAND driver.
Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/au1550nd.c

@@ -602,8 +602,6 @@ module_init(au1xxx_nand_init);
  */
 static void __exit au1550_cleanup(void)
 {
-	struct nand_chip *this = (struct nand_chip *)&au1550_mtd[1];
-
 	/* Release resources, unregister device */
 	nand_release(au1550_mtd);