tracing/ftrace: replace none tracer by nop tracer

Replace "none" tracer by the recently created "nop" tracer.
Both are pretty similar except that nop accepts TRACE_PRINT
or TRACE_SPECIAL entries.

And as a consequence, changing the size of the ring buffer now
requires that tracing has already been disabled.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace_nop.c b/kernel/trace/trace_nop.c
index 9fb02c1..16c9ba0 100644
--- a/kernel/trace/trace_nop.c
+++ b/kernel/trace/trace_nop.c
@@ -51,7 +51,7 @@
 		stop_nop_trace(tr);
 }
 
-static struct tracer nop_trace __read_mostly =
+struct tracer nop_trace __read_mostly =
 {
 	.name		= "nop",
 	.init		= nop_trace_init,
@@ -62,8 +62,3 @@
 #endif
 };
 
-__init static int init_nop_trace(void)
-{
-	return register_tracer(&nop_trace);
-}
-device_initcall(init_nop_trace);