mtd: nand: remove unnecessary 'extern' from function declarations

'extern' is not necessary for function declarations. To prevent
people from adding the keyword to new declarations remove the
existing ones.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
[Linux commit: 79022591839f110f465cac0223e117b91d47d5db]
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

include/linux/mtd/nand.h

@@ -28,20 +28,20 @@ struct nand_flash_dev;
 struct device_node;
 
 /* Scan and identify a NAND device */
-extern int nand_scan(struct mtd_info *mtd, int max_chips);
+int nand_scan(struct mtd_info *mtd, int max_chips);
 /*
  * Separate phases of nand_scan(), allowing board driver to intervene
  * and override command or ECC setup according to flash type.
  */
-extern int nand_scan_ident(struct mtd_info *mtd, int max_chips,
+int nand_scan_ident(struct mtd_info *mtd, int max_chips,
 			   struct nand_flash_dev *table);
-extern int nand_scan_tail(struct mtd_info *mtd);
+int nand_scan_tail(struct mtd_info *mtd);
 
 /* Free resources held by the NAND device */
-extern void nand_release(struct mtd_info *mtd);
+void nand_release(struct mtd_info *mtd);
 
 /* Internal helper for board drivers which need to override command function */
-extern void nand_wait_ready(struct mtd_info *mtd);
+void nand_wait_ready(struct mtd_info *mtd);
 
 /*
  * This constant declares the max. oobsize / page, which
@@ -899,13 +899,13 @@ struct nand_manufacturers {
 extern struct nand_flash_dev nand_flash_ids[];
 extern struct nand_manufacturers nand_manuf_ids[];
 
-extern int nand_default_bbt(struct mtd_info *mtd);
-extern int nand_markbad_bbt(struct mtd_info *mtd, loff_t offs);
-extern int nand_isreserved_bbt(struct mtd_info *mtd, loff_t offs);
-extern int nand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt);
-extern int nand_erase_nand(struct mtd_info *mtd, struct erase_info *instr,
+int nand_default_bbt(struct mtd_info *mtd);
+int nand_markbad_bbt(struct mtd_info *mtd, loff_t offs);
+int nand_isreserved_bbt(struct mtd_info *mtd, loff_t offs);
+int nand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt);
+int nand_erase_nand(struct mtd_info *mtd, struct erase_info *instr,
 			   int allowbbt);
-extern int nand_do_read(struct mtd_info *mtd, loff_t from, size_t len,
+int nand_do_read(struct mtd_info *mtd, loff_t from, size_t len,
 			size_t *retlen, uint8_t *buf);
 
 /*