staging: gdm724x: fix gdm_lte_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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gdm724x/gdm_lte.c

@@ -408,7 +408,7 @@ static s32 gdm_lte_tx_nic_type(struct net_device *dev, struct sk_buff *skb)
 	return nic_type;
 }
 
-static int gdm_lte_tx(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t gdm_lte_tx(struct sk_buff *skb, struct net_device *dev)
 {
 	struct nic *nic = netdev_priv(dev);
 	u32 nic_type;