r8169: remove unneeded call to netif_stop_queue in rtl8169_net_suspend

netif_device_detach() stops all tx queues already, so we don't need
this call.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>