ps2: don't raise an interrupt if queue is full

ps2_queue() behaves differently than the very similar functions
ps2_queue_2() to ps2_queue_4(). The first one calls update_irq()
even if the queue is full, the others don't. Change ps2_queue()
to be consistent with the others.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-Id: <20210525181441.27768-2-vr_qemu@t-online.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hw/input/ps2.c

@@ -212,6 +212,10 @@ void ps2_raise_irq(PS2State *s)
 
 void ps2_queue(PS2State *s, int b)
 {
+    if (PS2_QUEUE_SIZE - s->queue.count < 1) {
+        return;
+    }
+
     ps2_queue_noirq(s, b);
     s->update_irq(s->update_arg, 1);
 }