8139cp: reset BQL when ring tx ring cleared

[ Upstream commit 98962baa ]

This patch cures transmit timeout's with DHCP observed
while running under KVM. When the transmit ring is cleaned out,
the Byte Queue Limit values need to be reset.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/ethernet/realtek/8139cp.c

@@ -1097,6 +1097,7 @@ static void cp_clean_rings (struct cp_private *cp)
 			cp->dev->stats.tx_dropped++;
 		}
 	}
+	netdev_reset_queue(cp->dev);
 
 	memset(cp->rx_ring, 0, sizeof(struct cp_desc) * CP_RX_RING_SIZE);
 	memset(cp->tx_ring, 0, sizeof(struct cp_desc) * CP_TX_RING_SIZE);