Added missing getRaw

include/aidge/backend/cuda/data/TensorImpl.hpp

@@ -58,7 +58,11 @@ class TensorImpl_cuda : public TensorImpl, public TensorImpl_cuda_  {
     void *rawPtr() override {
         lazyInit(reinterpret_cast<void**>(&mData));
         return mData;
-    };
+    }
+
+    void* getRaw(std::size_t idx) {
+        return static_cast<void*>(static_cast<T*>(rawPtr()) + idx);
+    }
 
     const cudnnTensorDescriptor_t& getCudnnTensorDesc() const override {
         if (mCudnnTensor == nullptr) {