sched/core: Fix some documentation build warnings

The kerneldoc comments for try_to_wake_up_local() were out of date, leading
to these documentation build warnings:

  ./kernel/sched/core.c:2080: warning: No description found for parameter 'rf'
  ./kernel/sched/core.c:2080: warning: Excess function parameter 'cookie' description in 'try_to_wake_up_local'

Update the comment to reflect current reality and give us some peace and
quiet.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/20170724135628.695cecfc@lwn.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/core.c

@@ -2069,7 +2069,7 @@ out:
 /**
  * try_to_wake_up_local - try to wake up a local task with rq lock held
  * @p: the thread to be awakened
- * @cookie: context's cookie for pinning
+ * @rf: request-queue flags for pinning
  *
  * Put @p on the run-queue if it's not already there. The caller must
  * ensure that this_rq() is locked, @p is bound to this_rq() and not