[AOT]Aot module post-test error workaround (#13685)

The deletion of the AotModule python object results in the device shutting down RPC too early, causing an assertion in the DSP. This is a temporary workaround while this is still being investigated. The workaround is to keep a reference to the AotModule object in the HexagonSession object, so it stays until the session has been shut down.

python/tvm/contrib/hexagon/session.py

@@ -248,8 +248,9 @@ def get_aot_executor(
         GraphModule :
             Runtime graph module that can be used to execute the graph.
         """
-        aot_mod = self.load_module(module_file)
-        return tvm.runtime.executor.AotModule(aot_mod["default"](self.device))
+        # Temporary workaround for https://github.com/apache/tvm/issues/13741
+        self.aot_mod = self.load_module(module_file)
+        return tvm.runtime.executor.AotModule(self.aot_mod["default"](self.device))
 
     def get_graph_debug_executor(
         self,