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/video/vt8623fb.c b/drivers/video/vt8623fb.c
index 8bc6e09..5c7cbc6 100644
--- a/drivers/video/vt8623fb.c
+++ b/drivers/video/vt8623fb.c
@@ -729,7 +729,7 @@
 
 	vga_res.flags = IORESOURCE_IO;
 
-	pcibios_bus_to_resource(dev, &vga_res, &bus_reg);
+	pcibios_bus_to_resource(dev->bus, &vga_res, &bus_reg);
 
 	par->state.vgabase = (void __iomem *) vga_res.start;