stop_machine: Add caller debug info to queue_stop_cpus_work

Most callsites were covered by commit

  a8b62fd0 ("stop_machine: Add function and caller debug info")

but this skipped queue_stop_cpus_work(). Add caller debug info to it.
Signed-off-by: NValentin Schneider <valentin.schneider@arm.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201210163830.21514-2-valentin.schneider@arm.com

kernel/stop_machine.c

@@ -409,6 +409,7 @@ static bool queue_stop_cpus_work(const struct cpumask *cpumask,
 		work->fn = fn;
 		work->arg = arg;
 		work->done = done;
+		work->caller = _RET_IP_;
 		if (cpu_stop_queue_work(cpu, work))
 			queued = true;
 	}