Fix netboot on some Apple machines on which calling dma-free on the

network device can hang the machine. This causes the loss of 64 KB of
accessible memory on netbooted machines.

sys/boot/ofw/libofw/ofw_net.c

@@ -230,7 +230,10 @@ ofwn_init(struct iodesc *desc, void *machdep_hint)
 static void
 ofwn_end(struct netif *nif)
 {
+#ifdef BROKEN
+	/* dma-free freezes at least some Apple ethernet controllers */
 	OF_call_method("dma-free", netinstance, 2, 0, dmabuf, MAXPHYS);
+#endif
 	OF_close(netinstance);
 }