webadmin: fixed layout of total VCPUs editor

The broken layout was caused by using custom styling
of the widget with info icon.

Fixed by using the standard EntityModelWidgetWithInfo widget.

Change-Id: Iadb78a9bba4c98d5189463a19471e248c2e3f902
Signed-off-by: Tomas Jelinek <tjelinek@redhat.com>
Bug-Url: https://bugzilla.redhat.com/1105468