tracing/function-return-tracer: change the name into function-graph-tracer

Impact: cleanup

This patch changes the name of the "return function tracer" into
function-graph-tracer which is a more suitable name for a tracing
which makes one able to retrieve the ordered call stack during
the code flow.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index d02a0ca..7ad48f2 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1365,7 +1365,7 @@
 	unsigned long default_timer_slack_ns;
 
 	struct list_head	*scm_work_list;
-#ifdef CONFIG_FUNCTION_RET_TRACER
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	/* Index of current stored adress in ret_stack */
 	int curr_ret_stack;
 	/* Stack of return addresses for return function tracing */