selftests: tc-testing: report number of workers in use

Report the number of workers in use to process the test batches.
Since the number is now subject to a limit, avoid users getting
confused.

Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://lore.kernel.org/r/20231117171208.2066136-7-pctammela@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/tc-testing/tdc.py

@@ -616,7 +616,7 @@ def test_runner_mp(pm, args, alltests):
     batches.insert(0, serial)
 
     print("Executing {} tests in parallel and {} in serial".format(len(parallel), len(serial)))
-    print("Using {} batches".format(len(batches)))
+    print("Using {} batches and {} workers".format(len(batches), args.mp))
 
     # We can't pickle these objects so workaround them
     global mp_pm