Only set persistent-net name if device is specified

persistent-net should not use the warewulf interface name as a default device
name because the network configuration scripts don't.

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

overlays/wwinit/etc/systemd/network/10-persistent-net.link.ww

@@ -5,14 +5,10 @@
 {{range $devname, $netdev := .NetDevs}}
 {{- $filename := print "10-persistent-net-" $devname ".link"}}
 {{- file $filename }}
-{{- if $netdev.Hwaddr }}
+{{- if and $netdev.Hwaddr $netdev.Device }}
 [Match]
 MACAddress={{$netdev.Hwaddr}}
 [Link]
-{{ if $netdev.Device -}}
 Name={{ $netdev.Device }}
-{{ else -}}
-Name={{ $devname }}
-{{ end -}}
 {{ end -}}
 {{end}}