PCI: Replace printk(KERN_INFO) with pr_info(), etc

Replace printk() with pr_*() to be more consistent with other logging and
avoid checkpatch warnings.

Link: https://lore.kernel.org/lkml/1555733026-19609-1-git-send-email-mohankumar718@gmail.com
Link: https://lore.kernel.org/lkml/1555733130-19804-1-git-send-email-mohankumar718@gmail.com
Signed-off-by: Mohan Kumar <mohankumar718@gmail.com>
[bhelgaas: squash in similar changes from second patch in series]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c
index c46d5e1..f4d92b1 100644
--- a/drivers/pci/slot.c
+++ b/drivers/pci/slot.c
@@ -403,7 +403,7 @@ static int pci_slot_init(void)
 	pci_slots_kset = kset_create_and_add("slots", NULL,
 						&pci_bus_kset->kobj);
 	if (!pci_slots_kset) {
-		printk(KERN_ERR "PCI: Slot initialization failure\n");
+		pr_err("PCI: Slot initialization failure\n");
 		return -ENOMEM;
 	}
 	return 0;