tcp: rack the request level logging is a bit too noisy when doing point logging.

When doing request level BB logging the hybrid_bw_log() does not have proper screening to minimize logging
when point level logging is in use. Lets fix it properly so you have to have the proper knobs set to get the
more noisy logging.

Reviewed by: tuexen
Sponsored by: Netflix Inc
Differential Revision:https://reviews.freebsd.org/D39699