[LV] Update LoopVectorizationPlanner::emitInvalidCostRemarks to handle reduction plans

Issue #165359.

TypeSwitch did not handle the case of retrieving the opcode from a VPRedutionPlan type.

Author: bababuck

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -3971,6 +3971,9 @@ void LoopVectorizationPlanner::emitInvalidCostRemarks(
             .Case<VPInterleaveRecipe>([](const VPInterleaveRecipe *R) {
               return R->getStoredValues().empty() ? Instruction::Load
                                                   : Instruction::Store;
+            })
+            .Case<VPReductionRecipe>([](const auto *R) {
+              return RecurrenceDescriptor::getOpcode(R->getRecurrenceKind());
             });
 
     // If the next recipe is different, or if there are no other pairs,