[llvm] [VPlan] Replace RdxDesc with RecurKind in VPReductionPHIRecipe (NFC). (PR #142322)

[via llvm-commits]

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@@ -301,6 +301,11 @@ class LoopVectorizationLegality {
   /// Returns the reduction variables found in the loop.
   const ReductionList &getReductionVars() const { return Reductions; }
 
+  RecurrenceDescriptor getRecurrenceDescriptor(PHINode *PN) const {
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ayalz wrote:

```suggestion
  /// Returns the recurrence descriptor associated with a given phi node \p PN,
  /// expecting one to exist.
  RecurrenceDescriptor getRecurrenceDescriptor(PHINode *PN) const {
```

https://github.com/llvm/llvm-project/pull/142322