[X86] negateFMAOpcode - extend to support FMADDSUB/FMSUBADD and output negation. NFCI.
[X86] negateFMAOpcode - extend to support FMADDSUB/FMSUBADD and output negation. NFCI.

Some prep work for PR42863, this change allows us to move all the FMA opcode mappings into the negateFMAOpcode helper.

For the FMADDSUB/FMSUBADD cases, we can only negate the accumulator - any other negations will result in an error.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@371840 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm