ACPI: asus_acpi: Do not load if no device has been found

asus_acpi_init() has a hack to prevent the driver from loading
when asus_hotk_add() fails.  However, it was returning the successful
return value of acpi_bug_registger_driver() on failure.  This caused
an oops on unload.  Instead it should return -ENODEV.
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/asus_acpi.c

@@ -1398,7 +1398,7 @@ static int __init asus_acpi_init(void)
 	if (!asus_hotk_found) {
 		acpi_bus_unregister_driver(&asus_hotk_driver);
 		remove_proc_entry(PROC_ASUS, acpi_root_dir);
-		return result;
+		return -ENODEV;
 	}
 
 	asus_backlight_device = backlight_device_register("asus",NULL,NULL,