[llvm] [TableGen] Improve handling for dag op names (PR #149248)

[Nemanja Ivanovic via llvm-commits]

nemanjai wrote:

> Can you fix the clang-format failures shown in CI? I'll take a look at the updates soon

But the clang-format failures are due to me rejecting clang-format changes as per your suggestion here: https://github.com/llvm/llvm-project/pull/149248#discussion_r2224454718

https://github.com/llvm/llvm-project/pull/149248