pkg/emb6: update to use iolists

pkg/emb6/contrib/netdev/emb6_netdev.c

@@ -138,11 +138,11 @@ static int8_t _netdev_init(s_ns_t *p_ns)
 static int8_t _netdev_send(const void *pr_payload, uint8_t c_len)
 {
     if (_dev != NULL) {
-        const struct iovec vector = {
-            .iov_base = (void *)pr_payload,
-            .iov_len = c_len
+        iolist_t iolist = {
+            .iol_base = (void *)pr_payload,
+            .iol_len = c_len,
         };
-        if (_dev->driver->send(_dev, &vector, 1) < 0) {
+        if (_dev->driver->send(_dev, &iolist) < 0) {
             DEBUG("Error on send\n");
             return RADIO_TX_ERR;
         }