ieee1394: prevent device binding of raw1394, video1394, dv1394

These drivers don't need to match any unit_directory type device.
They just need the id_table for module autoloading per module alias.

Not binding any of these drivers allows special-purpose drivers with
similar or same IDs to bind to devices.  This currently only benefits
out-of-tree drivers; on the other hand it is in no way detrimental to
in-tree drivers.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/ieee1394/nodemgr.c b/drivers/ieee1394/nodemgr.c
index 511e432..70afa37 100644
--- a/drivers/ieee1394/nodemgr.c
+++ b/drivers/ieee1394/nodemgr.c
@@ -701,7 +701,11 @@
 		return 0;
 
 	driver = container_of(drv, struct hpsb_protocol_driver, driver);
-	for (id = driver->id_table; id->match_flags != 0; id++) {
+	id = driver->id_table;
+	if (!id)
+		return 0;
+
+	for (; id->match_flags != 0; id++) {
 		if ((id->match_flags & IEEE1394_MATCH_VENDOR_ID) &&
 		    id->vendor_id != ud->vendor_id)
 			continue;