pfctl: print counters in decimal

795d78a46713 pfctl: Don't use PRIu64 mistakenly changed these to be
printed as hexadecimal numbers.

Reported by: Florian Smeets
MFC after: 4 days
Sponsored by: Rubicon Communications, LLC ("Netgate")

(cherry picked from commit 846a6e8f9ab25df4e06d28c05fb66060d803c9ba)