tracing: Add MODULE_DESCRIPTION() to preemptirq_delay_test

Fix the 'make W=1' warning:

WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/trace/preemptirq_delay_test.o

Link: https://lore.kernel.org/linux-trace-kernel/20240518-md-preemptirq_delay_test-v1-1-387d11b30d85@quicinc.com

Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: f96e8577 ("lib: Add module for testing preemptoff/irqsoff latency tracers")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

kernel/trace/preemptirq_delay_test.c

@@ -215,4 +215,5 @@ static void __exit preemptirq_delay_exit(void)
 
 module_init(preemptirq_delay_init)
 module_exit(preemptirq_delay_exit)
+MODULE_DESCRIPTION("Preempt / IRQ disable delay thread to test latency tracers");
 MODULE_LICENSE("GPL v2");