alpine: drop hints from interface configuration

Turns out ifupdown-ng ignores "inet static" and "inet loopback" hints
on iface lines. The interface named "lo" is always used as loopback.

roles/alpine/templates/interfaces.j2

@@ -1,7 +1,7 @@
 {# Loopback interface must be present so define it here if none exists. #}
 {% if interfaces | rejectattr("name", "==", "lo") %}
 auto lo
-iface lo inet loopback
+iface lo
 
 {% endif -%}
 
@@ -12,7 +12,7 @@ iface lo inet loopback
     | rejectattr('mgmt_only')
     | selectattr('enabled') %}
 auto {{ iface.name }}
-iface {{ iface.name }} inet {% if iface.name == "lo" %}loopback{% else %}static{% endif +%}
+iface {{ iface.name }}
 {% if iface.mtu %}
     mtu {{ iface.mtu }}
 {% endif %}