[IOTCELL-1182] User TX priority over automatic uplinks

In the case when an automatic uplink was queued and the user do have something send,
we should give priority to user data instead od automatic uplink message.

Author: Hasnain Virk

features/lorawan/LoRaWANStack.cpp

@@ -805,8 +805,12 @@ void LoRaWANStack::send_event_to_application(const lorawan_event_t event) const
 
 void LoRaWANStack::send_automatic_uplink_message(const uint8_t port)
 {
+    // we will silently ignore the automatic uplink event if the user is already
+    // sending something
     const int16_t ret = handle_tx(port, NULL, 0, MSG_CONFIRMED_FLAG, true, true);
-    if (ret < 0) {
+    if (ret == LORAWAN_STATUS_WOULD_BLOCK) {
+        _automatic_uplink_ongoing = false;
+    } else if (ret < 0) {
         tr_debug("Failed to generate AUTOMATIC UPLINK, error code = %d", ret);
         send_event_to_application(AUTOMATIC_UPLINK_ERROR);
     }