tracing: consolidate code between trace_output.c and trace_function_graph.c

Both trace_output.c and trace_function_graph.c do basically the same
thing to handle the printing of the latency-format. This patch moves
the code into one function that both can use.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace_output.h

@@ -26,6 +26,8 @@ extern struct trace_event *ftrace_find_event(int type);
 
 extern enum print_line_t trace_nop_print(struct trace_iterator *iter,
 					 int flags);
+extern int
+trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry);
 
 /* used by module unregistering */
 extern int __unregister_ftrace_event(struct trace_event *event);