[Ovmsdev] Fix to esp-idf for adjusting logging levels

If you have observed that sometimes when you try to adjust logging levels using the OVMS command "level" that the change is not effective, the explanation is that the logging code in esp-idf uses a cache to speed the level lookup but the call to set the level did not update the cache. I've fixed that in openvehicles/esp-idf just now. -- Steve