Merge branch 'fix/ble_mesh_trans_pending_fix' into 'master'

fix(ble_mesh): remove tx pending assert

Closes BLERP-1801

See merge request espressif/esp-idf!38640

Author: Isl2017

components/bt/esp_ble_mesh/core/transport.c

@@ -388,8 +388,9 @@ static void schedule_retransmit(struct seg_tx *tx)
      * the seg_pending of this segment.
      * See BLEMESH25-92 for details */
     if (tx->dst == BLE_MESH_ADDR_UNASSIGNED) {
-        assert(tx->seg_pending == 1);
-        tx->seg_pending = 0;
+        if (tx->seg_pending) {
+            tx->seg_pending--;
+        }
         return;
     }