ACPI / hotplug: Set kobject name via kobject_add(), not kobject_set_name()

Set the kobject name via kobject_add() instead of using kobject_set_name(),
which is deprecated per Documentation/kobject.txt.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>