tracing: Restore original format of sched events

The original format for sched_stat_iowait and sched_stat_sleep:

  $ cat events/sched/sched_stat_iowait/format
  ...
  print fmt: "comm=%s pid=%d delay=%Lu [ns]", ...
  $ cat events/sched/sched_stat_sleep/format
  ...
  print fmt: "comm=%s pid=%d delay=%Lu [ns]", ...

But commit commit 75ec29ab
("tracing: Convert some sched trace events to DEFINE_EVENT and
_PRINT") broke the format:

  $ cat events/sched/sched_stat_iowait/format
  print fmt: "task: %s:%d iowait: %Lu [ns]", ...
  $ cat events/sched/sched_stat_sleep/format
  print fmt: "task: %s:%d sleep: %Lu [ns]", ...

No change in functionality.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4B0E2951.9050800@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>