net: nfp: fix nfp_net_tx()'s return type

The method ndo_start_xmit() is defined as returning an 'netdev_tx_t',
which is a typedef for an enum type, but the implementation in this
driver returns an 'int'.

Fix this by returning 'netdev_tx_t' in this driver too.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfp_net_common.c

@@ -974,7 +974,7 @@ static int nfp_net_prep_tx_meta(struct sk_buff *skb, u64 tls_handle)
  *
  * Return: NETDEV_TX_OK on success.
  */
-static int nfp_net_tx(struct sk_buff *skb, struct net_device *netdev)
+static netdev_tx_t nfp_net_tx(struct sk_buff *skb, struct net_device *netdev)
 {
 	struct nfp_net *nn = netdev_priv(netdev);
 	const skb_frag_t *frag;