ACPICA: Namespace: Properly null terminate objects detached from a namespace node

Fixes a bug exposed by an ACPICA unit test around the
acpi_attach_data()/acpi_detach_data() APIs where the failure to null
terminate a detached object led to the creation of a circular linked list
(and infinite looping) when the object is reattached.

Reported in acpica bugzilla #1063

Link: https://bugs.acpica.org/show_bug.cgi?id=1063
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Cc: 3.15+ <stable@vger.kernel.org> # 3.15+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>