Do not apply these explicit unroll pragmas for ROCm. (#18204)
Summary:
Loop analysis indicates that there is a runtime trip count and hence
unrolling cannot take place.
This will silence compile-time warnings we have been observing with recent ROCm releases.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18204
Differential Revision: D14539875
Pulled By: ezyang
fbshipit-source-id: a7ea7f2a95603754296b76a6b62a154f56f4ad4d
