PCI: Add pci_bus_find_ext_capability

For use by code that needs to walk extended capability lists before
pci_dev structures are set up.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
LKML-Reference: <43F901BD926A4E43B106BF17856F07559FB80CFD@orsmsx508.amr.corp.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/include/linux/pci.h b/include/linux/pci.h
index c1968f4..65f8a8f 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -631,6 +631,8 @@
 int pci_find_capability(struct pci_dev *dev, int cap);
 int pci_find_next_capability(struct pci_dev *dev, u8 pos, int cap);
 int pci_find_ext_capability(struct pci_dev *dev, int cap);
+int pci_bus_find_ext_capability(struct pci_bus *bus, unsigned int devfn,
+				int cap);
 int pci_find_ht_capability(struct pci_dev *dev, int ht_cap);
 int pci_find_next_ht_capability(struct pci_dev *dev, int pos, int ht_cap);
 struct pci_bus *pci_find_next_bus(const struct pci_bus *from);