ACPICA: AcpiGetSleepTypeData: Allow \_Sx to return either 1 or 2 integers

Although the ACPI spec defines the \_Sx objects to return
a package containing one integer, most BIOS code returns two
integers and the previous code reflects that. However, we also
need to support BIOS code that actually implements to the ACPI
spec, and this change implements this.

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>