remove field name from HA discovery for single-field messages

contrib/etc/ebusd/mqtt-hassio.cfg

@@ -52,6 +52,7 @@
 #   %field the field name and key for JSON objects (equals the field index if no name is defined or the names are not
 #     unique in the message).
 #   %fieldname the field name (and nothing else like in %field, might be empty though!)
+#   %fieldnamemult the field name unless there is a single field only (similar to %fieldname)
 #   %type the field type (one of "number", "list", "string", "date", "time", or "datetime").
 #   %basetype the base data type ID (e.g. "UCH").
 #   %comment the field comment (if any).
@@ -350,7 +351,7 @@ definition-topic ?= %haprefix/%type_topic/%{TOPIC}_%FIELD/config
 # HA integration: this is the config topic payload for HA's MQTT discovery.
 definition-payload = {
   "unique_id":"%{TOPIC}_%FIELD",
-  "name":"%name %fieldname",
+  "name":"%name %fieldnamemult",
   "device":%circuit_part,
   "value_template":"{{value_json[\"%field\"].value}}",
   "state_topic":"%topic"%field_payload