usb: Fix linker errors with CONFIG_PM=n

Fix these linker errors when CONFIG_PM=n:

ERROR: "xhci_bus_resume" [drivers/usb/host/xhci-hcd.ko] undefined!
ERROR: "xhci_bus_suspend" [drivers/usb/host/xhci-hcd.ko] undefined!

Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 7f2f63c..fef5a1f 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -742,9 +742,4 @@
 	return 0;
 }
 
-#else
-
-#define	xhci_bus_suspend	NULL
-#define	xhci_bus_resume		NULL
-
-#endif
+#endif	/* CONFIG_PM */