wilc1000: let wilc_mac_xmit() return NETDEV_TX_OK

The method ndo_start_xmit() is defined as returning an 'netdev_tx_t',
which is a typedef for an enum type defining 'NETDEV_TX_OK' but this
driver returns '0' instead of 'NETDEV_TX_OK'.

Fix this by returning 'NETDEV_TX_OK' instead of '0'.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200629104009.84077-1-luc.vanoostenryck@gmail.com

drivers/net/wireless/microchip/wilc1000/netdev.c

@@ -684,14 +684,14 @@ netdev_tx_t wilc_mac_xmit(struct sk_buff *skb, struct net_device *ndev)
 
 	if (skb->dev != ndev) {
 		netdev_err(ndev, "Packet not destined to this device\n");
-		return 0;
+		return NETDEV_TX_OK;
 	}
 
 	tx_data = kmalloc(sizeof(*tx_data), GFP_ATOMIC);
 	if (!tx_data) {
 		dev_kfree_skb(skb);
 		netif_wake_queue(ndev);
-		return 0;
+		return NETDEV_TX_OK;
 	}
 
 	tx_data->buff = skb->data;
@@ -716,7 +716,7 @@ netdev_tx_t wilc_mac_xmit(struct sk_buff *skb, struct net_device *ndev)
 		srcu_read_unlock(&wilc->srcu, srcu_idx);
 	}
 
-	return 0;
+	return NETDEV_TX_OK;
 }
 
 static int wilc_mac_close(struct net_device *ndev)