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>