Revert r267098 - [MachineCombiner] Support for floating-point FMA on ARM64

It introduced buildbot failures on clang-cmake-mips, clang-ppc64le-linux, among others.

llvm-svn: 267127
diff --git a/llvm/lib/CodeGen/TargetInstrInfo.cpp b/llvm/lib/CodeGen/TargetInstrInfo.cpp
index 800ad6d..86517d9 100644
--- a/llvm/lib/CodeGen/TargetInstrInfo.cpp
+++ b/llvm/lib/CodeGen/TargetInstrInfo.cpp
@@ -655,11 +655,7 @@
 
   return false;
 }
-/// Return true when a code sequence can improve loop throughput.
-bool
-TargetInstrInfo::isThroughputPattern(MachineCombinerPattern Pattern) const {
-  return false;
-}
+
 /// Attempt the reassociation transformation to reduce critical path length.
 /// See the above comments before getMachineCombinerPatterns().
 void TargetInstrInfo::reassociateOps(