ACPICA: Fix for possible memory leak and fault.

Fixed a possible memory leak and fault in acpi_ex_resolve_object_to_value()
during a read from a buffer or region field. (BZ 458)

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>