cam: clear on-stack CCBs in last few drivers

This changes ahc(4), ahd(4), hptiop(4), hptnr(4), hptrr(4),
and ps3cdrom(4).

Reviewed By: imp
Sponsored by: NetApp, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D30305