[LV][NFC] Remove the declaration of function fixReduction. (#88491)

Author: Mel-Chen

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -616,9 +616,6 @@ class InnerLoopVectorizer {
   void fixFixedOrderRecurrence(VPFirstOrderRecurrencePHIRecipe *PhiR,
                                VPTransformState &State);
 
-  /// Create code for the loop exit value of the reduction.
-  void fixReduction(VPReductionPHIRecipe *Phi, VPTransformState &State);
-
   /// Iteratively sink the scalarized operands of a predicated instruction into
   /// the block that was created for it.
   void sinkScalarOperands(Instruction *PredInst);