client: log error on refresh

Report failure when trying to refresh client information.

src/client.c

@@ -881,6 +881,8 @@ static int og_resp_refresh(json_t *data, struct og_client *cli)
 	og_boot_entry_free(&boot_entry_list);
 	return 0;
 err_out:
+	syslog(LOG_ERR, "Failed to refresh info from client %s\n",
+	       inet_ntoa(cli->addr.sin_addr));
 	og_cache_image_free(&cache_list);
 	og_boot_entry_free(&boot_entry_list);
 	return -1;