rtla/osnoise: Distinguish missing workload option

osnoise_set_workload returns -1 for both missing OSNOISE_WORKLOAD option
and failure in setting the option.

Return -1 for missing and -2 for failure to distinguish them.

Cc: stable@vger.kernel.org
Cc: John Kacur <jkacur@redhat.com>
Cc: Luis Goncalves <lgoncalv@redhat.com>
Link: https://lore.kernel.org/20250107144823.239782-2-tglozar@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tools/tracing/rtla/src/osnoise.c

@@ -867,7 +867,7 @@ int osnoise_set_workload(struct osnoise_context *context, bool onoff)
 
 	retval = osnoise_options_set_option("OSNOISE_WORKLOAD", onoff);
 	if (retval < 0)
-		return -1;
+		return -2;
 
 	context->opt_workload = onoff;