Register grid buffers for Super_SloMo. (#2038)
Summary:
This PR registers both `gridX` and `gridY` as buffers for the `backWarp` module, which belongs to the `Super_SloMo` benchmark.
Without this PR, those buffers wouldn't be moved to a device on `model.to(device)`. This causes problems, specifically with XLA.
Pull Request resolved: https://github.com/pytorch/benchmark/pull/2038
Test Plan:
```
PJRT_DEVICE=CPU python benchmarks/dynamo/torchbench.py --performance --trace-on-xla --backend openxla --inference --only Super_SloMo
```
Reviewed By: aaronenyeshi
Differential Revision: D51367773
Pulled By: xuzhao9
fbshipit-source-id: bf05b5320c9dd4f46ffa466611bdfee0c20ee90f
