nvdimm acpi: compile nvdimm acpi code arch-independently

As the arch dependent info, TARGET_PAGE_SIZE, has been dropped
from nvdimm acpi code, it can be compiled arch-independently

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>
