HW Relnotes: Remove traces of cy, rc, rp drivers

These drivers were removed for FreeBSD 13.0. Remove what remains of
them from the hardware release notes template as well as the notes for
versions they did not ship with.

Ref: aa6ea9b6ce25 (remove some long abandoned serial drivers)
Discussed with: emaste, imp
Reviewed by: mhorne
Approved by: mhorne (mentor)
Differential Revision: https://reviews.freebsd.org/D50522