switch ext2 to simple_fsync()

kill ext2_sync_file() (along with ext2/fsync.c), get rid of
ext2_update_inode() - it's an alias of ext2_write_inode().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ext2/ext2.h

@@ -113,9 +113,6 @@ extern int ext2_empty_dir (struct inode *);
 extern struct ext2_dir_entry_2 * ext2_dotdot (struct inode *, struct page **);
 extern void ext2_set_link(struct inode *, struct ext2_dir_entry_2 *, struct page *, struct inode *);
 
-/* fsync.c */
-extern int ext2_sync_file (struct file *, struct dentry *, int);
-
 /* ialloc.c */
 extern struct inode * ext2_new_inode (struct inode *, int);
 extern void ext2_free_inode (struct inode *);