Fix a warning on 64-bit for a length value. Cast to 32-bit since
the length is related to an ACPI table.
Signed-off-by: NBob Moore <robert.moore@intel.com>
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>