PCI: add generic pcibios_resource_to_bus()

This replaces the generic versions of pcibios_resource_to_bus() and
pcibios_bus_to_resource() in asm-generic/pci.h with versions that use
pci_resource_to_bus() and pci_bus_to_resource().

The replacements are equivalent except that they can apply host
bridge window offsets when the arch has supplied them by using
pci_add_resource_offset().

Each arch can convert to using pci_add_resource_offset() individually by
removing its device resource fixups from pcibios_fixup_bus() and supplying
ARCH_HAS_GENERIC_PCI_OFFSETS.  ARCH_HAS_GENERIC_PCI_OFFSETS can be removed
after all have converted.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 3539171..a677b1e 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -118,6 +118,22 @@
 	res->end = region->end + offset;
 }
 
+#ifdef ARCH_HAS_GENERIC_PCI_OFFSETS
+void pcibios_resource_to_bus(struct pci_dev *dev, struct pci_bus_region *region,
+			     struct resource *res)
+{
+	pci_resource_to_bus(dev, region, res);
+}
+EXPORT_SYMBOL(pcibios_resource_to_bus);
+
+void pcibios_bus_to_resource(struct pci_dev *dev, struct resource *res,
+			     struct pci_bus_region *region)
+{
+	pci_bus_to_resource(dev, res, region);
+}
+EXPORT_SYMBOL(pcibios_bus_to_resource);
+#endif
+
 /*
  * PCI Bus Class
  */