isofs: switch to ->iterate_shared()

Signed-off-by: Al Viro <[e-mail]>

fs/isofs/dir.c

···
 {
 	.llseek = generic_file_llseek,
 	.read = generic_read_dir,
-	.iterate = isofs_readdir,
+	.iterate_shared = isofs_readdir,
 };
 
 /*