mac802154: make mac802154_wpan_open static

This function is only used within the same translation unit, so mark it
static.
Signed-off-by: NPhoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/mac802154/wpan.c

@@ -124,7 +124,7 @@ void mac802154_get_mac_params(struct net_device *dev,
 	mutex_unlock(&priv->hw->slaves_mtx);
 }
 
-int mac802154_wpan_open(struct net_device *dev)
+static int mac802154_wpan_open(struct net_device *dev)
 {
 	int rc;
 	struct mac802154_sub_if_data *priv = netdev_priv(dev);