[mlir][NFC] Remove some redundant code.

mlir/lib/Dialect/Arithmetic/IR/ArithmeticOps.cpp

return constFoldBinaryOp<IntegerAttr>(operands,
                                         });
 }
 
 //===----------------------------------------------------------------------===//
 // MulFOp
 //===----------------------------------------------------------------------===//
 
 OpFoldResult arith::MulFOp::fold(ArrayRef<Attribute> operands) {
-  APFloat floatValue(0.0f), inverseValue(0.0f);
   // mulf(x, 1) -> x
   if (matchPattern(getRhs(), m_OneFloat()))
     return getLhs();
 
-  // mulf(1, x) -> x
-  if (matchPattern(getLhs(), m_OneFloat()))
-    return getRhs();
-
   return constFoldBinaryOp<FloatAttr>(
       operands, [](const APFloat &a, const APFloat &b) { return a * b; });
 }
 
 //===----------------------------------------------------------------------===//
 // DivFOp
 //===----------------------------------------------------------------------===//
 
 OpFoldResult arith::DivFOp::fold(ArrayRef<Attribute> operands) {
-  APFloat floatValue(0.0f), inverseValue(0.0f);
   // divf(x, 1) -> x
   if (matchPattern(getRhs(), m_OneFloat()))
     return getLhs();
 
   return constFoldBinaryOp<FloatAttr>(
       operands, [](const APFloat &a, const APFloat &b) { return a / b; });
 }