cam: make sure to clear even more CCBs allocated on the stack

This is my second pass, this time over all of CAM except
for the SCSI target bits. There should be no functional
changes.

Reviewed By: imp
Sponsored by: NetApp, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D29549

(cherry picked from commit ec5325dbca629d65179f14f68bbcdb9c014f1523)