tracing/filter: Add missing initialization

Add missing initialization for ret variable. Its initialization
is based on the re_cnt variable, which is being set deep down
in the ftrace_function_filter_re function.

I'm not sure compilers would be smart enough to see this in near
future, so killing the warning this way.

Link: http://lkml.kernel.org/r/[email protected]

Signed-off-by: Jiri Olsa <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>

kernel/trace/trace_events_filter.c

@@ -2002,7 +2002,7 @@ static int ftrace_function_set_regexp(struct ftrace_ops *ops, int filter,
 static int __ftrace_function_set_filter(int filter, char *buf, int len,
 					struct function_filter_data *data)
 {
-	int i, re_cnt, ret;
+	int i, re_cnt, ret = -EINVAL;
 	int *reset;
 	char **re;