tracing: Rename set_ftrace to set_bootup_ftrace

Do this rename because set_ftrace is too much generic and not enough
self-explainable as a name.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4506826..866daf8 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -129,7 +129,7 @@
 static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;
 static char *default_bootup_tracer;
 
-static int __init set_ftrace(char *str)
+static int __init set_bootup_ftrace(char *str)
 {
 	strncpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
 	default_bootup_tracer = bootup_tracer_buf;
@@ -137,7 +137,7 @@
 	ring_buffer_expanded = 1;
 	return 1;
 }
-__setup("ftrace=", set_ftrace);
+__setup("ftrace=", set_bootup_ftrace);
 
 static int __init set_ftrace_dump_on_oops(char *str)
 {