ACPICA: Events: Fix uninitialized variable

ACPICA commit 8e21180050270897499652e922c6a41b8eb388b6

Recent changes to acpi_ev_asynch_execute_gpe_method left Status
variable uninitialized before use. Initialize to AE_OK.

Link: https://github.com/acpica/acpica/commit/8e211800


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