PCI: Export pci_find_host_bridge() for use inside PCI core

The find_pci_host_bridge() function can be useful to other PCI code so
export it.  Change its name to pci_find_host_bridge().

Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 4091f82..d72f849 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -321,4 +321,6 @@
 }
 #endif
 
+struct pci_host_bridge *pci_find_host_bridge(struct pci_bus *bus);
+
 #endif /* DRIVERS_PCI_H */