lint fix

Author: LeiWang1999

src/transform/arg_binder.cc

@@ -197,7 +197,7 @@ void ArgBinder::BindDLTensor(const Buffer &buffer, const PrimExpr &device_type,
   init_nest_.emplace_back(
       LetStmt(is_null_var,
               Call(DataType::Bool(), builtin::isnullptr(), {handle}), nop));
-  const PrimExpr& is_null = is_null_var;
+  const PrimExpr &is_null = is_null_var;
 
   // dimension checks
   PrimExpr v_ndim = TVMArrayGet(tvm_ndim_type, handle, builtin::kArrNDim);