usm_ndarray constructor with shape=() returns instance with __sycl_usm_array_interface__ having shape=None

```
In [32]: dpt.usm_ndarray(tuple(), dtype='d').__sycl_usm_array_interface__
Out[32]:
{'data': (93900589073280, True),
'shape': None,
'strides': None,
'typestr': '|f8',
'version': 1,
'syclobj': <dpctl.SyclQueue at 0x7f0cb8534f80>,
'offset': 0}
```

@Alexander-Makaryev 