IVGCVSW-4692 HAL 1.3 VTS/NNT, Unit test Failures

* Check if the model is prepared.

Signed-off-by: Sadik Armagan <sadik.armagan@arm.com>
Change-Id: Ia6ea7c5b61a1da97acddddfc5431925cbb4f0227
diff --git a/test/Convolution2D.hpp b/test/Convolution2D.hpp
index 38216f1..c471fbd 100644
--- a/test/Convolution2D.hpp
+++ b/test/Convolution2D.hpp
@@ -104,7 +104,10 @@
     float* outdata = reinterpret_cast<float*>(static_cast<void*>(outMemory->getPointer()));
 
     // run the execution
-    Execute(preparedModel, request);
+    if (preparedModel.get() != nullptr)
+    {
+        Execute(preparedModel, request);
+    }
 
     // check the result
     switch (paddingScheme)