fat: constify fatent_operations structures

The fatent_operations structures are never modified, so declare them as
const.

Done with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 4307cd4..e6b764a 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -87,7 +87,7 @@
 	unsigned int vol_id;		/*volume ID*/
 
 	int fatent_shift;
-	struct fatent_operations *fatent_ops;
+	const struct fatent_operations *fatent_ops;
 	struct inode *fat_inode;
 	struct inode *fsinfo_inode;