[PATCH] export pci_bus_type to modules.

This exports the pci_bus_type symbol to modules, needed by (at least)
the recent changes in pcmcia/cardbus.c.

drivers/pci/pci-driver.c

@@ -210,3 +210,4 @@ EXPORT_SYMBOL(pci_match_device);
 EXPORT_SYMBOL(pci_register_driver);
 EXPORT_SYMBOL(pci_unregister_driver);
 EXPORT_SYMBOL(pci_dev_driver);
+EXPORT_SYMBOL(pci_bus_type);