nvdimm acpi: emulate dsm method

Emulate dsm method after IO VM-exit

Currently, we only introduce the framework and no function is actually
supported

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
