net: sxgbe: fix potential NULL dereference in sxgbe_rx()

Currently, when skb is null, the driver prints an error and then
dereferences skb on the next line.

To fix this, let's add a 'break' after the error message to switch
to sxgbe_rx_refill(), which is similar to the approach taken by the
other drivers in this particular case, e.g. calxeda with xgmac_rx().

Found during a code review.

Fixes: 1edb9ca69e8a ("net: sxgbe: add basic framework for Samsung 10Gb ethernet driver")
Signed-off-by: Alexey Kodanev <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c

···
 
 		skb = priv->rxq[qnum]->rx_skbuff[entry];
 
-		if (unlikely(!skb))
+		if (unlikely(!skb)) {
 			netdev_err(priv->dev, "rx descriptor is not consistent\n");
+			break;
+		}
 
 		prefetch(skb->data - NET_IP_ALIGN);
 		priv->rxq[qnum]->rx_skbuff[entry] = NULL;