Use underlying ports counters to get lagg statistics instead of
per-packet accounting.
This introduce user-visible changes like aggregating error counters.

Reviewed by:	asomers (prev.version), glebius
CR:		D781
MFC after:	2 weeks
Sponsored by:	Yandex LLC


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272211 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f