Fix the FIXME that was just added in r217390 - remove a bunch of redundant fold permutations.

The testcases for these folds already exist in test/CodeGen/X86/fp-fast.ll.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217393 91177308-0d34-0410-b5e6-96231b3b80d8