PCI: Don't try to claim IORESOURCE_UNSET resources

If the IORESOURCE_UNSET bit is set, it means we haven't assigned an address
yet, so don't try to claim the region.

Also, make the error messages more uniform and add info about which BAR is
involved.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index 7f76521..6e443135 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -111,18 +111,23 @@
 	struct resource *res = &dev->resource[resource];
 	struct resource *root, *conflict;
 
+	if (res->flags & IORESOURCE_UNSET) {
+		dev_info(&dev->dev, "can't claim BAR %d %pR: no address assigned\n",
+			 resource, res);
+		return -EINVAL;
+	}
+
 	root = pci_find_parent_resource(dev, res);
 	if (!root) {
-		dev_info(&dev->dev, "no compatible bridge window for %pR\n",
-			 res);
+		dev_info(&dev->dev, "can't claim BAR %d %pR: no compatible bridge window\n",
+			 resource, res);
 		return -EINVAL;
 	}
 
 	conflict = request_resource_conflict(root, res);
 	if (conflict) {
-		dev_info(&dev->dev,
-			 "address space collision: %pR conflicts with %s %pR\n",
-			 res, conflict->name, conflict);
+		dev_info(&dev->dev, "can't claim BAR %d %pR: address conflict with %s %pR\n",
+			 resource, res, conflict->name, conflict);
 		return -EBUSY;
 	}