Don't check if there's a non-rendered output twice

We are already doing it on the line above.

plugins/platforms/wayland/wayland_backend.cpp

@@ -745,11 +745,6 @@ void WaylandBackend::checkBufferSwap()
         // TODO: what if one does not need to be rendered (no damage)?
         return;
     }
-
-    for (auto *output : m_outputs) {
-        if (!output->rendered()) {
-            return;
-        }
     Compositor::self()->bufferSwapComplete();
 
     for (auto *output : qAsConst(m_outputs)) {