tracing, thermal: Hide devfreq trace events when not in use

As trace events when defined create data structures and functions to
process them, defining trace events when not using them is a waste of
memory.

The trace events thermal_power_devfreq_get_power and
thermal_power_devfreq_limit are only used when CONFIG_DEVFREQ_THERMAL
is set. Make those events only defined when that is set as well.

Link: http://lkml.kernel.org/r/20171013102150.0050cb74@gandalf.local.home

Acked-by: Javi Merino <javi.merino@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

include/trace/events/thermal.h

@@ -148,6 +148,7 @@ TRACE_EVENT(thermal_power_cpu_limit,
 		__entry->power)
 );
 
+#ifdef CONFIG_DEVFREQ_THERMAL
 TRACE_EVENT(thermal_power_devfreq_get_power,
 	TP_PROTO(struct thermal_cooling_device *cdev,
 		 struct devfreq_dev_status *status, unsigned long freq,
@@ -203,6 +204,7 @@ TRACE_EVENT(thermal_power_devfreq_limit,
 		__get_str(type), __entry->freq, __entry->cdev_state,
 		__entry->power)
 );
+#endif /* CONFIG_DEVFREQ_THERMAL */
 #endif /* _TRACE_THERMAL_H */
 
 /* This part must be outside protection */