[VPlan] Merge Select with previous cases in ::computeCost (NFC).

Merge cases calling the same helper, as suggested post-commit in
llvm/llvm-project#174234

Author: fhahn

llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp

@@ -2283,7 +2283,6 @@ InstructionCost VPWidenRecipe::computeCost(ElementCount VF,
   case Instruction::ExtractValue:
   case Instruction::ICmp:
   case Instruction::FCmp:
-    return getCostForRecipeWithOpcode(getOpcode(), VF, Ctx);
   case Instruction::Select:
     return getCostForRecipeWithOpcode(getOpcode(), VF, Ctx);
   default: