COMPMID-1283: (GitHub issue) after convolution output data is zero

During the mutating passes accessors of optimized nodes were dropped
instead of being transfered to appropriate tensors.

Change-Id: I29183984d94806bdfb5c92af3acefd928c0fd171
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/136036
Reviewed-by: Anthony Barbier <anthony.barbier@arm.com>
Tested-by: Jenkins <bsgcomp@arm.com>
diff --git a/src/graph/Tensor.cpp b/src/graph/Tensor.cpp
index 287e783..ef253fe 100644
--- a/src/graph/Tensor.cpp
+++ b/src/graph/Tensor.cpp
@@ -67,6 +67,11 @@
     return _accessor.get();
 }
 
+std::unique_ptr<ITensorAccessor> Tensor::extract_accessor()
+{
+    return std::move(_accessor);
+}
+
 bool Tensor::call_accessor()
 {
     // Early exit guard