PCI: cpqphp: Fix possible null pointer dereference

There is otherwise a risk of a null pointer dereference.

Found by cppcheck, a static code analysis program.
Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/hotplug/cpqphp_ctrl.c

@@ -709,7 +709,8 @@ static struct pci_resource *get_max_resource(struct pci_resource **head, u32 siz
 				temp = temp->next;
 			}
 
-			temp->next = max->next;
+			if (temp)
+				temp->next = max->next;
 		}
 
 		max->next = NULL;