kprobes: adjust "fix a memory leak in function pre_handler_kretprobe()"

3.0.21's 603b6348 directly used
the upstream patch, yet kprobes locking in 3.0.x uses spin_lock...()
rather than raw_spin_lock...().
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

kernel/kprobes.c

@@ -1661,9 +1661,9 @@ static int __kprobes pre_handler_kretprobe(struct kprobe *p,
 		ri->task = current;
 
 		if (rp->entry_handler && rp->entry_handler(ri, regs)) {
-			raw_spin_lock_irqsave(&rp->lock, flags);
+			spin_lock_irqsave(&rp->lock, flags);
 			hlist_add_head(&ri->hlist, &rp->free_instances);
-			raw_spin_unlock_irqrestore(&rp->lock, flags);
+			spin_unlock_irqrestore(&rp->lock, flags);
 			return 0;
 		}