Apply clang-tidy fixes for llvm-qualified-auto in VectorUnroll.cpp (NFC)

Author: joker-eph

mlir/lib/Dialect/Vector/Transforms/VectorUnroll.cpp

@@ -311,7 +311,7 @@ struct UnrollContractionPattern
           applyPermutationMap(accPermutationMap, ArrayRef<int64_t>(offsets));
       // If a version of the accumulator has already been computed, use it
       // otherwise extract the first version from the original operand.
-      auto accIt = accCache.find(accOffets);
+      auto *accIt = accCache.find(accOffets);
       if (accIt != accCache.end())
         slicesOperands[2] = accIt->second;
       else
@@ -387,7 +387,7 @@ struct UnrollMultiReductionPattern
       SmallVector<int64_t> accStrides(destOffset.size(), 1);
       // If a version of the accumulator has already been computed, use it
       // otherwise extract the first version from the original operand.
-      auto accIt = accCache.find(destOffset);
+      auto *accIt = accCache.find(destOffset);
       if (accIt != accCache.end())
         acc = accIt->second;
       else