Fix typo that can prevent undercloud installation.

The interface to sdk.network.segments use network_id, not network[1].

Closes-Bug: #1748199

[1] https://github.com/openstack/python-openstacksdk/blob/master/openstack/network/v2/segment.py#L30..L34

Change-Id: Ibda590103ed8b02a1ce05e285a3d9d9ea2e2ff7f

instack_undercloud/undercloud.py

@@ -2035,7 +2035,7 @@ def _ensure_neutron_network(sdk):
             LOG.info("Network created %s", network)
             # (hjensas) Delete the default segment, we create a new segment
             # per subnet later.
-            segments = list(sdk.network.segments(network=network.id))
+            segments = list(sdk.network.segments(network_id=network.id))
             sdk.network.delete_segment(segments[0].id)
             LOG.info("Default segment on network %s deleted.", network.name)
         else: