[PATCH -rt] drop spurious rcu unlock

Strange rcu_read_unlock() which causes a imbalance, and boot hang.. I
didn't notice a reason for it, and removing it allows my system to make
progress.

This should go into the preempt-realtime-sched.patch

Signed-Off-By: Daniel Walker <redacted>

Index: linux-2.6.22.1/kernel/sched.c
===================================================================

--- linux-2.6.22.1.orig/kernel/sched.c	2007-07-22 16:47:37.000000000 +0000
+++ linux-2.6.22.1/kernel/sched.c	2007-07-22 16:16:48.000000000 +0000

@@ -4900,7 +4900,6 @@ asmlinkage long sys_sched_yield(void)
 	 * no need to preempt or enable interrupts:
 	 */
 	spin_unlock_no_resched(&rq->lock);
-	rcu_read_unlock();
 
 	__schedule();