Fix unused variable 'options' warning in RNN.cpp (#88753)
Fixes
```
/home/rbarnes/pytorch/aten/src/ATen/native/cudnn/RNN.cpp:73:17: warning: unused variable 'options' [-Wunused-variable]
TensorOptions options = TensorOptions().dtype(dtype).layout(layout).device(device).pinned_memory(pin_memory);
^
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/88753
Approved by: https://github.com/soumith
