PCI: Delay enabling bridges until they're needed

We currently enable PCI bridges after scanning a bus and assigning
resources.  This is often done in arch code.

This patch changes this so we don't enable a bridge until necessary, i.e.,
until we enable a PCI device behind the bridge.  We do this in the generic
pci_enable_device() path, so this also removes the arch-specific code to
enable bridges.

[bhelgaas: changelog]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pcmcia/cardbus.c

@@ -91,7 +91,6 @@ int __ref cb_alloc(struct pcmcia_socket *s)
 	if (s->tune_bridge)
 		s->tune_bridge(s, bus);
 
-	pci_enable_bridges(bus);
 	pci_bus_add_devices(bus);
 
 	return 0;