trace/osnoise: Fix return value on osnoise_init_hotplug_support

kernel test robot reported:

  >> kernel/trace/trace_osnoise.c:1584:2: error: void function
  'osnoise_init_hotplug_support' should not return a
  value [-Wreturn-type]
           return 0;

When !CONFIG_HOTPLUG_CPU.

Fix it problem by removing the return value.

Link: https://lkml.kernel.org/r/c7fc67f1a117cc88bab2e508c898634872795341.1624872608.git.bristot@redhat.com

Fixes: c8895e27 ("trace/osnoise: Support hotplug operations")
Reported-by: Nkernel test robot <lkp@intel.com>
Signed-off-by: NDaniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/trace_osnoise.c

@@ -1586,7 +1586,7 @@ static void osnoise_init_hotplug_support(void)
 #else /* CONFIG_HOTPLUG_CPU */
 static void osnoise_init_hotplug_support(void)
 {
-	return 0;
+	return;
 }
 #endif /* CONFIG_HOTPLUG_CPU */