tracing: Add missing "inline" in stub function of latency_fsnotify()

The latency_fsnotify() stub when the function is not defined, was missing
the "inline".

Link: https://lore.kernel.org/r/20191115140213.74c5efe7@canb.auug.org.auReported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/trace.h

@@ -801,7 +801,7 @@ void latency_fsnotify(struct trace_array *tr);
 
 #else
 
-static void latency_fsnotify(struct trace_array *tr) { }
+static inline void latency_fsnotify(struct trace_array *tr) { }
 
 #endif