[llvm] [NVPTX] Add family-specific architectures support (PR #141899)

[Rajat Bajpai via llvm-commits]

rajatbajpai wrote:

Guys, I have tried to fix the nits. If this change looks good overall, I would prefer to merge this and refine as we go. So, I'll appreciate an upvote. Thanks for understanding.

https://github.com/llvm/llvm-project/pull/141899