nand: constify id/manu tables

These id tables need not be writable.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 94ad0c0..519f47e 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -470,8 +470,8 @@
 	char * name;
 };
 
-extern struct nand_flash_dev nand_flash_ids[];
-extern struct nand_manufacturers nand_manuf_ids[];
+extern const struct nand_flash_dev nand_flash_ids[];
+extern const struct nand_manufacturers nand_manuf_ids[];
 
 extern int nand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd);
 extern int nand_update_bbt(struct mtd_info *mtd, loff_t offs);