[nrf fromtree] Bluetooth: Mesh: add extension config server by lcd server

Commit add extension of configuration server by large
composition data server.
Mesh Protocol v1.1 specification
4.4.21.1
The Large Composition Data Server is a main model
that extends the Configuration Server model.

Signed-off-by: Aleksandr Khromykh <[email protected]>
(cherry picked from commit f9d7385)

Author: alxelax

subsys/bluetooth/mesh/Kconfig

@@ -1167,6 +1167,7 @@ endif # BT_MESH_OP_AGG_CLI
 
 config BT_MESH_LARGE_COMP_DATA_SRV
 	bool "Support for Large Composition Data Server Model"
+	depends on BT_MESH_MODEL_EXTENSIONS
 	help
 	  Enable support for the Large Composition Data Server model.
 

subsys/bluetooth/mesh/large_comp_data_srv.c

@@ -170,8 +170,11 @@ const struct bt_mesh_model_op _bt_mesh_large_comp_data_srv_op[] = {
 
 static int large_comp_data_srv_init(const struct bt_mesh_model *model)
 {
-	if (!bt_mesh_model_in_primary(model)) {
-		LOG_ERR("Large Composition Data Server only allowed in primary element");
+	const struct bt_mesh_model *config_srv =
+		bt_mesh_model_find(bt_mesh_model_elem(model), BT_MESH_MODEL_ID_CFG_SRV);
+
+	if (config_srv == NULL) {
+		LOG_ERR("Large Composition Data Server cannot extend Configuration server");
 		return -EINVAL;
 	}
 
@@ -181,6 +184,8 @@ static int large_comp_data_srv_init(const struct bt_mesh_model *model)
 
 	srv.model = model;
 
+	bt_mesh_model_extend(model, config_srv);
+
 	return 0;
 }