tracing/fastboot: only trace non-module initcalls

At this time, only built-in initcalls interest us.
We can't really produce a relevant graph if we include
the modules initcall too.

I had good results after this patch (see svg in attachment).

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

init/main.c

@@ -886,6 +886,7 @@ static int __init kernel_init(void * unused)
 	 * we're essentially up and running. Get rid of the
 	 * initmem segments and start the user-mode stuff..
 	 */
+	stop_boot_trace();
 	init_post();
 	return 0;
 }