[POWERPC] Fix incorrect calculation of I/O window addresses

My patch "Cope with PCI host bridge I/O window not starting at 0"
introduced a bug in the calculation of the virtual addresses for the
I/O windows of PCI host bridges other than the first, because it
didn't account for the fact that hose->io_resource gets offset so that
it reflects the range of global I/O port numbers assigned to the
bridge.  This fixes it and simplifies get_bus_io_range() in the
process.
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/pci_64.c

@@ -1098,35 +1098,24 @@ static int get_bus_io_range(struct pci_bus *bus, unsigned long *start_phys,
 				unsigned long *start_virt, unsigned long *size)
 {
 	struct pci_controller *hose = pci_bus_to_host(bus);
-	struct pci_bus_region region;
 	struct resource *res;
 
-	if (bus->self) {
+	if (bus->self)
 		res = bus->resource[0];
-		pcibios_resource_to_bus(bus->self, &region, res);
-		*start_phys = hose->io_base_phys + region.start;
-		*start_virt = (unsigned long) hose->io_base_virt + 
-				region.start;
-		if (region.end > region.start) 
-			*size = region.end - region.start + 1;
-		else {
-			printk("%s(): unexpected region 0x%lx->0x%lx\n", 
-					__FUNCTION__, region.start, region.end);
-			return 1;
-		}
-		
-	} else {
+	else
 		/* Root Bus */
 		res = &hose->io_resource;
-		*start_phys = hose->io_base_phys + res->start;
-		*start_virt = (unsigned long) hose->io_base_virt + res->start;
-		if (res->end > res->start)
-			*size = res->end - res->start + 1;
-		else {
-			printk("%s(): unexpected region 0x%lx->0x%lx\n", 
-					__FUNCTION__, res->start, res->end);
-			return 1;
-		}
+
+	*start_virt = pci_io_base + res->start;
+	*start_phys = *start_virt + hose->io_base_phys
+		- (unsigned long) hose->io_base_virt;
+
+	if (res->end > res->start)
+		*size = res->end - res->start + 1;
+	else {
+		printk("%s(): unexpected region 0x%lx->0x%lx\n",
+		       __FUNCTION__, res->start, res->end);
+		return 1;
 	}
 
 	return 0;