Give CentOS 8 installer explicit network device

Seems that install works without defining this but after install is
completed all interfaces are converted to DHCP which is default.

group_vars/centos8.yml

@@ -12,7 +12,7 @@ ipcmd: >-
   {%     set int=network_interfaces[0] %}
   {%     if int['ipaddr'] is defined and int['gateway'] is defined %}
   nameserver=8.8.8.8
-  ip={{ int['ipaddr'] }}::{{ int['gateway'] }}:{{ int['netmask'] }}:::none
+  ip={{ int['ipaddr'] }}::{{ int['gateway'] }}:{{ int['netmask'] }}::eth0:none
   {%     endif %}
   {%   endif %}
   {% endif %}