sched/wait: Fix wait_event_freezable() documentation

I noticed the comment label 'wait_event' was wrong.

Signed-off-by: Stafford Horne <shorne@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1456234768-24933-1-git-send-email-shorne@gmail.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>