net: stmmac: update rx tail pointer register to fix rx dma hang issue.

Currently we will not update the receive descriptor tail pointer in
stmmac_rx_refill. Rx dma will think no available descriptors and stop
once received packets exceed DMA_RX_SIZE, so that the rx only test will fail.

Update the receive tail pointer in stmmac_rx_refill to add more descriptors
to the rx channel, so packets can be received continually

Fixes: 54139cf3 ("net: stmmac: adding multiple buffers for rx")
Signed-off-by: Biao Huang <biao.huang@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -3338,6 +3338,7 @@ static inline void stmmac_rx_refill(struct stmmac_priv *priv, u32 queue)
 		entry = STMMAC_GET_ENTRY(entry, DMA_RX_SIZE);
 	}
 	rx_q->dirty_rx = entry;
+	stmmac_set_rx_tail_ptr(priv, priv->ioaddr, rx_q->rx_tail_addr, queue);
 }
 
 /**