FHSS: Increased min random of tx poll

Because of bad synchronization, unicast packet was sent
immediately after broadcast channel when receiver had not yet changed
to unicast.

source/Service_Libs/fhss/fhss_ws.c

@@ -163,12 +163,12 @@ static void fhss_broadcast_handler(const fhss_api_t *fhss_api, uint16_t delay)
         // Should return to own (unicast) listening channel after broadcast channel
         next_channel = fhss_structure->rx_channel;
         /* Start timer with random timeout to trigger unicast TX queue poll event.
-         * Min random is 50us.
+         * Min random is 1/30 of the TX slot length.
          * Max random is 1/10 of the TX slot length.
          * Event timer resolution is 50us.
          */
         uint32_t txrx_slot_length_us = fhss_structure->ws->txrx_slot_length_ms * 1000;
-        uint16_t uc_min_random = 1;
+        uint16_t uc_min_random = (txrx_slot_length_us / 30) / 50;
         uint16_t uc_max_random = (txrx_slot_length_us / 10) / 50;
         bool tx_allowed = fhss_ws_check_tx_allowed(fhss_structure);
         if (!tx_allowed) {