Bluetooth: Audio: Modify log of non-found stream for config state callback

In the unicast client, it is possible for the unicast server
to send a notification for ASE when it is in the codec
configured state after a reconnect. In that case, the
unicast client does not have a coupling between the ASE
and the audio stream.

This caused a BT_ERR to trigger, but it is not really an
error, but rather a state that the current unicast client
cannot handle, so the BT_ERR has been replaced with
a BT_WARN.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>

Author: Thalley

subsys/bluetooth/audio/unicast_client.c

@@ -518,7 +518,7 @@ static void unicast_client_ep_config_state(struct bt_audio_ep *ep,
 
 	stream = ep->stream;
 	if (stream == NULL) {
-		BT_ERR("No stream active for endpoint");
+		BT_WARN("No stream active for endpoint");
 		return;
 	}