Fix showing IPS IN USE from a large pool as 0
Fix showing IPS IN USE from a large pool as 0

We were calculating <large float64> - (<large float64> - <IPs in use>),
which gives 0 when <IPs in use> is small.  Fix that by removing that
calculation (which was unnecessary).

bcreane/calico,bcreane/calico,bcreane/calico,bcreane/calico,bcreane/calico,bcreane/calico