pf: extend use of skip steps for Ethernet rules

Use the already populated PFE_SKIP_DST_ADDR and extend the skip
infrastructure to also skip on IP source/destination addresses.

This should make evaluating the rules slightly faster.

Reported by: R. Christian McDonald <rcm@rcm.sh>
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D40567