cobalt/synch: Do not drop PP on xnsynch_release if it wasn't committed

We must not try to drop the prio ceiling in the kernel if it wasn't
committed yet. That could easily happen when using a prio-ceiling mutex
to wait on a cond-var.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

kernel/cobalt/synch.c

@@ -942,7 +942,7 @@ bool xnsynch_release(struct xnsynch *synch, struct xnthread *curr)
 	 */
 	xnlock_get_irqsave(&nklock, s);
 
-	if (synch->status & XNSYNCH_PP) {
+	if (synch->status & XNSYNCH_CEILING) {
 		clear_pp_boost(synch, curr);
 		need_resched = true;
 	}