tracing: disable tracepoints by default

while it's arguably low overhead, we dont enable new features by default.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

init/Kconfig

@@ -773,7 +773,6 @@ config PROFILING
 
 config TRACEPOINTS
 	bool "Activate tracepoints"
-	default y
 	help
 	  Place an empty function call at each tracepoint site. Can be
 	  dynamically changed for a probe function.