[clang] Mechanically convert NVPTX builtins to use TableGen (PR #122873)

[Chandler Carruth via cfe-commits]

chandlerc wrote:

> > ⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️
> 
> Note that the PR doesn't actually change the lines that `clang-format` changes here, and the `clang-format` change makes these lines inconsistent with the rest of the file, so I intentionally did not apply these formatting changes. My guess was that the community would prefer to not have deviations from the surrounding file introduced like this.

Well, I did this and wrote this reply after looking at the diff shown by `git`...

But looking at it in GitHub, this file is already inconsistent and many parts are clang-formatted. Nevermind, no real consistency argument. I've updated the PR to be formatted.

https://github.com/llvm/llvm-project/pull/122873