myri10ge: use eth_skb_pad helper

Update myri10ge to use eth_skb_pad helper.  This also corrects a minor
issue as the driver was updating length without updating the tail pointer.

Cc: Hyong-Youb Kim <hykim@myri.com>
Signed-off-by: NAlexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/myricom/myri10ge/myri10ge.c

@@ -2913,17 +2913,12 @@ static netdev_tx_t myri10ge_xmit(struct sk_buff *skb,
 		flags |= MXGEFW_FLAGS_SMALL;
 
 		/* pad frames to at least ETH_ZLEN bytes */
-		if (unlikely(skb->len < ETH_ZLEN)) {
-			if (skb_padto(skb, ETH_ZLEN)) {
+		if (eth_skb_pad(skb)) {
 			/* The packet is gone, so we must
 			 * return 0 */
 			ss->stats.tx_dropped += 1;
 			return NETDEV_TX_OK;
 		}
-			/* adjust the len to account for the zero pad
-			 * so that the nic can know how long it is */
-			skb->len = ETH_ZLEN;
-		}
 	}
 
 	/* map the skb for DMA */