ACPICA: Dispatcher: Fix a resource leak issue in acpi_ds_auto_serialize_method().

ACPICA commit 29d03840cbab435e8ea82e9339ff9d84535c647d

This patch fixes a resource leak issue in acpi_ds_auto_serialize_method().
It is reported by the "Coverity" tool as unsecure code. Lv Zheng.

Link: https://github.com/acpica/acpica/commit/29d03840
Link: https://jira01.devtools.intel.com/browse/LCK-2142


Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>