[llvm] [VPlan] Remove no longer needed VP intrinsic handling in VPWidenIntrinsicRecipe::computeCost. NFCI (PR #137573)

[Mel Chen via llvm-commits]

https://github.com/Mel-Chen approved this pull request.

LGTM.
There is an unrelated question: is there a possibility that the operand is not of vector type?
```
  SmallVector<Type *> ParamTys;
  for (unsigned I = 0; I != getNumOperands(); ++I)
    ParamTys.push_back(
        toVectorTy(Ctx.Types.inferScalarType(getOperand(I)), VF));
```

https://github.com/llvm/llvm-project/pull/137573