ACPICA: Fix memory leak on unusual memory leak

Fixes a single-object memory leak on a store-to-reference method
invocation. ACPICA BZ 1439.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Erik Schmauss <erik.schmauss@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>