PCIE: check and return bus_register errors

Have pcie_port_bus_register() notice and return errors.
Mark it __must_check so that its caller(s) must check its return value.

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
index 478d0d2..3284199 100644
--- a/drivers/pci/pcie/portdrv_pci.c
+++ b/drivers/pci/pcie/portdrv_pci.c
@@ -129,12 +129,17 @@
 
 static int __init pcie_portdrv_init(void)
 {
-	int retval = 0;
+	int retval;
 
-	pcie_port_bus_register();
+	retval = pcie_port_bus_register();
+	if (retval) {
+		printk(KERN_WARNING "PCIE: bus_register error: %d\n", retval);
+		goto out;
+	}
 	retval = pci_register_driver(&pcie_portdrv);
 	if (retval)
 		pcie_port_bus_unregister();
+ out:
 	return retval;
 }