tracing/ftrace: tracing engine depends on Nop Tracer

Now that the nop tracer is used as the default tracer by
replacing the "none" tracer, tracing engine depends on it.

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>

kernel/trace/Kconfig

@@ -1,8 +1,13 @@
 #
 # Architectures that offer an FTRACE implementation should select HAVE_FTRACE:
 #
+
+config NOP_TRACER
+	bool
+
 config HAVE_FTRACE
 	bool
+	select NOP_TRACER
 
 config HAVE_DYNAMIC_FTRACE
 	bool
@@ -101,16 +106,6 @@ config SCHED_TRACER
 	  This tracer tracks the latency of the highest priority task
 	  to be scheduled in, starting from the point it has woken up.
 
-config NOP_TRACER
-	bool "NOP Tracer"
-	depends on HAVE_FTRACE
-	depends on DEBUG_KERNEL
-	select TRACING
-	help
-	  This tracer does nothing. The primary purpose for it is to
-	  politely print the output of ftrace_printk() calls without
-	  the overhead of an irrelevant trace taking place.
-
 config CONTEXT_SWITCH_TRACER
 	bool "Trace process context switches"
 	depends on HAVE_FTRACE