[ARM GlobalISel] Add inst selector tests for G_FMA

We don't yet match all the patterns involving G_FMA. Add tests for some
of the ones that we do match.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@322368 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed