net: moxa: Prefer 'unsigned int' to bare use of 'unsigned'

Use 'unsigned int' instead of 'unsigned'
This warning is found using checkpatch.pl
Signed-off-by: SZ Lin <sz.lin@moxa.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/moxa/moxart_ether.c

@@ -288,8 +288,8 @@ static int moxart_tx_queue_space(struct net_device *ndev)
 static void moxart_tx_finished(struct net_device *ndev)
 {
 	struct moxart_mac_priv_t *priv = netdev_priv(ndev);
-	unsigned tx_head = priv->tx_head;
-	unsigned tx_tail = priv->tx_tail;
+	unsigned int tx_head = priv->tx_head;
+	unsigned int tx_tail = priv->tx_tail;
 
 	while (tx_tail != tx_head) {
 		dma_unmap_single(&ndev->dev, priv->tx_mapping[tx_tail],