smc91c111: Fix receive starvation

In case the smc91c111 interface signals that it cannot receive more
packets the packets are queued and further reception will be disabled.
In case the interface is again ready to receive packets notify the upper
layer.
Signed-off-by: NSebastian Huber <sebastian.huber@embedded-brains.de>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

hw/net/smc91c111.c

@@ -185,6 +185,7 @@ static void smc91c111_release_packet(smc91c111_state *s, int packet)
     s->allocated &= ~(1 << packet);
     if (s->tx_alloc == 0x80)
         smc91c111_tx_alloc(s);
+    qemu_flush_queued_packets(qemu_get_queue(s->nic));
 }
 
 /* Flush the TX FIFO.  */