hwgraph: Fixing error message

When hwgraph find an unsupported engine, it prints a message.
This message is using the engine module name as the engine name making a
confusing output.

This commit use the engine name instead of the engine module.

Signed-off-by: Erwan Velu <e.velu@criteo.com>

graph/trace.py

@@ -201,7 +201,7 @@ def prepare_perf_metrics(self) -> tuple[list, str]:
         em = self.engine_module()
         # Preparing the performance metric to graph
         if self.engine() not in ["stressng", "sleep"]:
-            fatal(f"Unsupported {em} engine")
+            fatal(f"Unsupported {self.engine()} engine")
         if self.engine() == "stressng":
             if em in ["cpu", "qsort", "vnni"]:
                 perf_list = ["bogo ops/s"]