ftrace: enable format arguments checking

Impact: broaden gcc printf format checks for ftrace_printk()

format arguments checking for ftrace_printk() is __printf(1, 2),
not __printf(1, 0).

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 04b52e6..677432b 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -303,7 +303,7 @@
 static inline void
 ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
 static inline int
-ftrace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 0)));
+ftrace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
 
 static inline void tracing_start(void) { }
 static inline void tracing_stop(void) { }