ACPICA: Add write support for DataTable operation regions

The original implementation only supported reading from a DataTable
region. However, some machines have been seen that actually write
to the ACPI table contained in such a region. This change adds
support for writing to a DataTable region.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>