[llvm] [CodeGenPrepare] Reverse the canonicalization of isInf/isNanOrInf (PR #81572)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> ping for review. X86 required this patch to fix below regression: https://gcc.godbolt.org/z/8P1do36qd

Still has the minor outstanding comment about checking legality 

https://github.com/llvm/llvm-project/pull/81572