nvdimm acpi: fix region format interface code

Per ACPI 6.2, section 5.2.25.6 and JEDEC Annex L Release 3, the
current region format interface code 0x201 indicates the block
addressed function interface 1, rather than a byte addressable
interface. Fix it by using 0x301 which indicates the byte addressable
no energy backed function interface 1.

Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>