pci: Fix INTx routing notifier recursion

For some reason we recurse to fire the INTx routing notifier for each
child of a bus, for each possible device of a bus.  That means that if
we add a root port, the notifier gets called for that bridge 256
times.  If we add an upstream switch behind that root port, 256^2.  But
of course we need a downstream switch, 256^3.  This starts to be
noticeable.  Stop the insanity.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/pci/pci.c

@@ -1215,9 +1215,10 @@ void pci_bus_fire_intx_routing_notifier(PCIBus *bus)
         if (dev && dev->intx_routing_notifier) {
             dev->intx_routing_notifier(dev);
         }
-        QLIST_FOREACH(sec, &bus->child, sibling) {
-            pci_bus_fire_intx_routing_notifier(sec);
-        }
+    }
+
+    QLIST_FOREACH(sec, &bus->child, sibling) {
+        pci_bus_fire_intx_routing_notifier(sec);
     }
 }