sched: Fix yield_to kernel-doc

Add missing function parameters for yield_to():

 Warning(kernel/sched.c:5470): No description found for parameter 'p'
 Warning(kernel/sched.c:5470): No description found for parameter 'preempt'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20110318093453.8f7489a4.randy.dunlap@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched.c

@@ -5467,6 +5467,8 @@ EXPORT_SYMBOL(yield);
  * yield_to - yield the current processor to another thread in
  * your thread group, or accelerate that thread toward the
  * processor it's on.
+ * @p: target task
+ * @preempt: whether task preemption is allowed or not
  *
  * It's the caller's job to ensure that the target task struct
  * can't go away on us before we can do any checks.