40network: handle 'ip=ifname:static' correctly

'static' configuration means 'apply the settings from the ifcfg file'.
Which might be either static or dhcp.
And for multiple configurations the first configuration can be
either dhcp or static; only the following configurations must
be static.

References: bnc#892801

Signed-off-by: Hannes Reinecke <hare@suse.de>