[llvm] [SDAG] Fix fmaximum legalization errors (PR #142170)

[Nikita Popov via llvm-commits]

nikic wrote:

Same issue exists for fmaximumnum. I have a fix for that, but https://github.com/llvm/llvm-project/pull/139237 needs to land first.

https://github.com/llvm/llvm-project/pull/142170