examples/parttool: fix the test to work on parallel test runner

Pass the DUT port to parttool_example.py as an argument.

examples/storage/parttool/example_test.py

@@ -34,7 +34,7 @@ def test_examples_parttool(env, extra_data):
             binary_path = flash_file[1]
             break
 
-    subprocess.check_call([sys.executable, script_path, "--binary", binary_path])
+    subprocess.check_call([sys.executable, script_path, "--binary", binary_path, "--port", dut.port])
 
 
 if __name__ == '__main__':