[llvm] [NFC][LLVM] Simplify `TypeInfoGen` in Intrinsics.td (PR #189278)

[Nikita Popov via llvm-commits]

nikic wrote:

I think what you are describing was the original intention and why the mapping exists. But at the same time, I don't think there is a particularly good reason why it should be that way, and it does add extra complexity. Having the index just unconditionally refer to the nth overload type parameter seems simpler.

https://github.com/llvm/llvm-project/pull/189278