Fix capping of VAPs

Fix capping of VAPs

The previous approach introduced a cap, but it might not always be hit as
intended (I missed this on review). Fix this to check the cap after merging
an ASPA into an already existing VAP. Also free the list of providers since
nothing should be looking at it anymore.

Count VAPs that hit the limit with a new overflowed counter. There are
still a few aspects of the accounting that probably aren't entirely right.
This will be fixed at another point. It's just statistics after all.

with/ok claudio, ok job