tracing/events: make SAMPLE_TRACE_EVENTS default to n

Normally a config should be default to n. This patch also makes the
sample module-only, like SAMPLE_MARKERS and SAMPLE_TRACEPOINTS.

[ Impact: don't build trace event sample by default ]
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A00F6C0.8090803@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

samples/Kconfig

@@ -20,9 +20,8 @@ config SAMPLE_TRACEPOINTS
 	  This build tracepoints example modules.
 
 config SAMPLE_TRACE_EVENTS
-	tristate "Build trace_events examples"
-	depends on EVENT_TRACING
-	default m
+	tristate "Build trace_events examples -- loadable modules only"
+	depends on EVENT_TRACING && m
 	help
 	  This build trace event example modules.