pf: bound DIOCGETSTATES memory use

Similar to what we did earlier for DIOCGETSTATESV2 we only allocate
enough memory for a handful of states and copy those out, bit by bit,
rather than allocating memory for all states in one go.

MFC after: 1 week
Sponsored by: Rubicon Communications, LLC ("Netgate")

(cherry picked from commit 600745f1e2260e7ed3c2e6183b24388ff38c916c)