add default interface for easy case

networkd/templates/20-wired-static.network.j2

 {% set network = {
-	'interface': item.1.interface|default(ansible_default_ipv4.interface),
+	'interface': item.1.interface|default(networkd_interface|default(ansible_default_ipv4.interface)),
 	'addresses': item.1.addresses|default([item.1.adress|default(networkd_address)]),
 	'gateway': item.1.gateway|default(networkd_gateway),
 	} %}