ftrace.h: Use common pr_info fmt string

Reduces fmt string space a bit.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1260651974.2637.4.camel@Joe-Laptop.home>
Signed-off-by: Ingo Molnar <mingo@elte.hu>