[llvm] [LLVM][Intrinsics] Print note if manual name matches default name (PR #164716)

[Rahul Joshi via llvm-commits]

jurahul wrote:

I also renamed the variable in CodeGenIntrinsics.cpp from `DerivedName` to `DefaultName` to match the wording of the note printed.

https://github.com/llvm/llvm-project/pull/164716