PCI: Convert pcibios_resource_to_bus() to take a pci_bus, not a pci_dev

These interfaces:

  pcibios_resource_to_bus(struct pci_dev *dev, *bus_region, *resource)
  pcibios_bus_to_resource(struct pci_dev *dev, *resource, *bus_region)

took a pci_dev, but they really depend only on the pci_bus.  And we want to
use them in resource allocation paths where we have the bus but not a
device, so this patch converts them to take the pci_bus instead of the
pci_dev:

  pcibios_resource_to_bus(struct pci_bus *bus, *bus_region, *resource)
  pcibios_bus_to_resource(struct pci_bus *bus, *resource, *bus_region)

In fact, with standard PCI-PCI bridges, they only depend on the host
bridge, because that's the only place address translation occurs, but
we aren't going that far yet.

[bhelgaas: changelog]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index 83c4d3b..5c060b1 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -52,7 +52,7 @@
 	if (res->flags & IORESOURCE_PCI_FIXED)
 		return;
 
-	pcibios_resource_to_bus(dev, &region, res);
+	pcibios_resource_to_bus(dev->bus, &region, res);
 
 	new = region.start | (res->flags & PCI_REGION_FLAG_MASK);
 	if (res->flags & IORESOURCE_IO)