Fix and enable DALI tests
This pull request **introduces 1 alert** when merging 760f3012e9f086af1d1893d0a1c378bd2b2aabab into bee43e840837d7e30e17a65b972e9fe89ecb9ca5 - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-7b0cbe4483c3653568bbc31df8b151ec2086aefc)

**new alerts:**

* 1 for Unused local variable
Signed-off-by: Joaquin Anton janton@nvidia.com