powerpc/PCI: compute I/O space bus-to-resource offset consistently

Make sure we compute CPU addresses (resource start/end) the same way both
when we set up the I/O aperture (hose->io_resource) and when we use
pcibios_bus_to_resource() to convert BAR values into resources.

This fixes a build failure ("cast from pointer to integer of different
size" in configs where resource_size_t is 64 bits but pointers are 32 bits)
I introduced in 6c5705fec63d.

Acked-By: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/arch/powerpc/kernel/pci_32.c b/arch/powerpc/kernel/pci_32.c
index fdd1a3d..4b06ec5 100644
--- a/arch/powerpc/kernel/pci_32.c
+++ b/arch/powerpc/kernel/pci_32.c
@@ -219,9 +219,9 @@
 	struct resource *res = &hose->io_resource;
 
 	/* Fixup IO space offset */
-	io_offset = (unsigned long)hose->io_base_virt - isa_io_base;
-	res->start = (res->start + io_offset) & 0xffffffffu;
-	res->end = (res->end + io_offset) & 0xffffffffu;
+	io_offset = pcibios_io_space_offset(hose);
+	res->start += io_offset;
+	res->end += io_offset;
 }
 
 static int __init pcibios_init(void)