math/fma: Add fp32 software implementation

Passes CTS on carrizo (when forced to use sw fma) and turks.
Reviewer: Tom Stellard <tstellar@redhat.com>
Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>

llvm-svn: 334226
GitOrigin-RevId: 6e85e6309d38393c2a4360f8232d5b11540a6aa4
7 files changed