Restore missing Huawei LTE cleanup on HA stop (#49871)

Refs https://github.com/home-assistant/core/pull/49788#discussion_r623071013

homeassistant/components/huawei_lte/__init__.py

@@ -39,6 +39,7 @@ from homeassistant.const import (
     CONF_RECIPIENT,
     CONF_URL,
     CONF_USERNAME,
+    EVENT_HOMEASSISTANT_STOP,
 )
 from homeassistant.core import CALLBACK_TYPE, HomeAssistant, ServiceCall
 from homeassistant.exceptions import ConfigEntryNotReady
@@ -442,6 +443,11 @@ async def async_setup_entry(hass: HomeAssistant, config_entry: ConfigEntry) -> b
         async_track_time_interval(hass, _update_router, SCAN_INTERVAL)
     )
 
+    # Clean up at end
+    config_entry.async_on_unload(
+        hass.bus.async_listen_once(EVENT_HOMEASSISTANT_STOP, router.cleanup)
+    )
+
     return True