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/dir.c

@@ -720,5 +720,5 @@ const struct file_operations ext2_dir_operations = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= ext2_compat_ioctl,
 #endif
-	.fsync		= ext2_sync_file,
+	.fsync		= simple_fsync,
 };