[X86] Remove unreachable code in X86TargetTransformInfo.cpp

In Function getVectorInstrCost, situation Opcode == Instruction::ExtractElement
and Opcode == Instruction::InsertElement are all handled in the first 2 if-statements,
So we have no chance for the code in line 4401.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D145908

llvm/lib/Target/X86/X86TargetTransformInfo.cpp

@@ -4396,11 +4396,6 @@ InstructionCost X86TTIImpl::getVectorInstrCost(unsigned Opcode, Type *Val,
     return ShuffleCost + IntOrFpCost + RegisterFileMoveCost;
   }
 
-  // Add to the base cost if we know that the extracted element of a vector is
-  // destined to be moved to and used in the integer register file.
-  if (Opcode == Instruction::ExtractElement && ScalarType->isPointerTy())
-    RegisterFileMoveCost += 1;
-
   return BaseT::getVectorInstrCost(Opcode, Val, CostKind, Index, Op0, Op1) +
          RegisterFileMoveCost;
 }