nvdimm acpi: introduce patched dsm memory

The dsm memory is used to save the input parameters and store
the dsm result which is filled by QEMU.

The address of dsm memory is decided by bios and patched into
int32 object named "MEMA"

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>
