tracing: preemptirq_delay_run() can be static

Automatically found by kbuild test robot.

Fixes: ffdc73a3b2ad ("lib: Add module for testing preemptoff/irqsoff latency tracers")
Signed-off-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/preemptirq_delay_test.c

@@ -34,7 +34,7 @@ static void busy_wait(ulong time)
 	} while (ktime_to_ns(ktime_sub(end, start)) < (time * 1000));
 }
 
-int preemptirq_delay_run(void *data)
+static int preemptirq_delay_run(void *data)
 {
 	unsigned long flags;