nvdimm acpi: set HDLE properly

Now we pass HDLE to Qemu properly, use 0 for root device and use the
handle for nvdimm devices

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