[AArch64] More @llvm.fma.f16 tests
[AArch64] More @llvm.fma.f16 tests

Follow up of rL371321 that added FMA FP16 patterns. This adds more tests
for @llvm.fma.f16. This probably shows we miss one fmsub optimisation
opportunity, which I will look into.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@371833 91177308-0d34-0410-b5e6-96231b3b80d8

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