lldp: do weird control structure stuff

lldp/init.sls

@@ -2,7 +2,7 @@
 {%- for name, interface in pillar.ifaces.items() if 'lldp' in interface -%}
   {%- do interfaces.append(name) -%}
 {%- endfor -%}
-{%- if interfaces is iterable -%}
+{%- if interfaces|length > 0 -%}
 lldpd:
   pkg.installed: []
   service.running: