Fix tracing sample code warning.

Commit 6575257c60e1 ("tracing/samples: Fix creation and deletion of
simple_thread_fn creation") introduced a new warning due to using a
boolean as a counter.

Just make it "int".

Fixes: 6575257c60e1 ("tracing/samples: Fix creation and deletion of simple_thread_fn creation")
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

samples/trace_events/trace-events-sample.c

@@ -78,7 +78,7 @@ static int simple_thread_fn(void *arg)
 }
 
 static DEFINE_MUTEX(thread_mutex);
-static bool simple_thread_cnt;
+static int simple_thread_cnt;
 
 int foo_bar_reg(void)
 {