On AMD GPUs it seems that `hipDeviceGetName` returns an empty string, so
when this is the case simply return the architecture instead, as this
what AMD OpenCL devices return for the name.

Before this patch:
```
Devices  : 1
    Device [#0]:
    Type       : gpu
    Version    : 0.0
    Name       :
    Vendor     : AMD Corporation
    Driver     : HIP 40421.43
```

After this patch:
```
Devices  : 1
    Device [#0]:
    Type       : gpu
    Version    : 0.0
    Name       : gfx908:sramecc+:xnack-
    Vendor     : AMD Corporation
    Driver     : HIP 40421.43
```