[Unifomity] Remove unused PhiInput definition (NFC) (llvm#161116)

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Author: perlfu

llvm/include/llvm/ADT/GenericUniformityImpl.h

@@ -408,15 +408,6 @@ template <typename ContextT> class GenericUniformityAnalysisImpl {
                                 const CycleT *);
 
 protected:
-  /// \brief Value/block pair representing a single phi input.
-  struct PhiInput {
-    ConstValueRefT value;
-    BlockT *predBlock;
-
-    PhiInput(ConstValueRefT value, BlockT *predBlock)
-        : value(value), predBlock(predBlock) {}
-  };
-
   const ContextT &Context;
   const FunctionT &F;
   const CycleInfoT &CI;