PCI: Fail pci_ioremap_bar() on unassigned resources

Make pci_ioremap_bar() fail if we're trying to map a BAR that hasn't been
assigned.

Normally pci_enable_device() will fail if a BAR hasn't been assigned, but a
driver can successfully call pci_enable_device_io() even if a memory BAR
hasn't been assigned.  That driver should not be able to use
pci_ioremap_bar() to map that unassigned memory BAR.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/pci/pci.c

@@ -131,7 +131,7 @@ void __iomem *pci_ioremap_bar(struct pci_dev *pdev, int bar)
 	/*
 	 * Make sure the BAR is actually a memory resource, not an IO resource
 	 */
-	if (!(res->flags & IORESOURCE_MEM)) {
+	if (res->flags & IORESOURCE_UNSET || !(res->flags & IORESOURCE_MEM)) {
 		dev_warn(&pdev->dev, "can't ioremap BAR %d: %pR\n", bar, res);
 		return NULL;
 	}