ACPI / sysfs: correctly check failing memory allocation

Since kobject_create_and_add() can fail under memory pressure,
its return value needs to be checked against NULL before passing
it to sysfs_create_file().
Signed-off-by: Insu Yun <wuninsu@gmail.com>
[ rjw: Subject & changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/sysfs.c

@@ -878,6 +878,9 @@ int __init acpi_sysfs_init(void)
 		return result;
 
 	hotplug_kobj = kobject_create_and_add("hotplug", acpi_kobj);
+	if (!hotplug_kobj)
+		return -ENOMEM;
+
 	result = sysfs_create_file(hotplug_kobj, &force_remove_attr.attr);
 	if (result)
 		return result;