Revert "Emit vector mulitply and accumulate instructions for x86."

This reverts commit 61908880e6565acfadbafe93fa64de000014f1a6.

Reason for revert: By failing to round multiply results, it does not follow Java rounding rules.

Change-Id: Ic0ef08691bef266c9f8d91973e596e09ff3307c6
diff --git a/compiler/optimizing/optimizing_compiler.cc b/compiler/optimizing/optimizing_compiler.cc
index bb33ba3..84863e4 100644
--- a/compiler/optimizing/optimizing_compiler.cc
+++ b/compiler/optimizing/optimizing_compiler.cc
@@ -530,8 +530,7 @@
         OptDef(OptimizationPass::kSideEffectsAnalysis),
         OptDef(OptimizationPass::kGlobalValueNumbering, "GVN$after_arch"),
         OptDef(OptimizationPass::kPcRelativeFixupsX86),
-        OptDef(OptimizationPass::kX86MemoryOperandGeneration),
-        OptDef(OptimizationPass::kInstructionSimplifierX86)
+        OptDef(OptimizationPass::kX86MemoryOperandGeneration)
       };
       return RunOptimizations(graph,
                               codegen,
@@ -546,8 +545,7 @@
       OptimizationDef x86_64_optimizations[] = {
         OptDef(OptimizationPass::kSideEffectsAnalysis),
         OptDef(OptimizationPass::kGlobalValueNumbering, "GVN$after_arch"),
-        OptDef(OptimizationPass::kX86MemoryOperandGeneration),
-        OptDef(OptimizationPass::kInstructionSimplifierX86)
+        OptDef(OptimizationPass::kX86MemoryOperandGeneration)
       };
       return RunOptimizations(graph,
                               codegen,