set size in the rootfs parameter on CT create

As the size parameter is now deprecated and was replaced with the
new rootfs parameter, use that one when creating an container.
So we don't get an 'parameter verification failed' error.
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

www/manager/lxc/CreateWizard.js

@@ -148,7 +148,7 @@ Ext.define('PVE.lxc.CreateWizard', {
 			storagesel,
 			{
 			    xtype: 'numberfield',
-			    name: 'size',
+			    name: 'rootfs',
 			    minValue: 0.1,
 			    maxValue: 128*1024,
 			    decimalPrecision: 3,