vlan edit: Set valid default name

Using find_next_iface_id we get a valid VLAN name.
This way, inserting a vlan raw device is still required (but everything that is
inserted so far is valid).

Signed-off-by: Dominic Jäger <d.jaeger@proxmox.com>

src/node/NetworkView.js

@@ -235,6 +235,7 @@ Ext.define('Proxmox.node.NetworkView', {
 		    let win = Ext.create('Proxmox.node.NetworkEdit', {
 			nodename: me.nodename,
 			iftype: 'vlan',
+			iface_default: find_next_iface_id('vlan'),
 			onlineHelp: 'sysadmin_network_configuration',
 		    });
 		    win.on('destroy', reload);