[X86] Add scalar FMA ISD nodes without rounding mode. NFC

Next step is to use them for the legacy FMA scalar intrinsics as well. This will enable the legacy intrinsics to use EVEX encoded opcodes and the extended registers.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@317453 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed