nvdimm: use NVDIMM_ACPI_IO_LEN for the proper IO size

The IO range is defined to 4 bytes with NVDIMM_ACPI_IO_LEN, so it is
more proper to use this macro instead of calculating it by sizeof.

Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Message-Id: <20190227075101.6263-4-richardw.yang@linux.intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>

hw/acpi/nvdimm.c

@@ -992,7 +992,7 @@ static void nvdimm_build_common_dsm(Aml *dev)
     field = aml_field(NVDIMM_DSM_IOPORT, AML_DWORD_ACC, AML_NOLOCK,
                       AML_PRESERVE);
     aml_append(field, aml_named_field(NVDIMM_DSM_NOTIFY,
-               sizeof(uint32_t) * BITS_PER_BYTE));
+               NVDIMM_ACPI_IO_LEN * BITS_PER_BYTE));
     aml_append(method, field);
 
     /*