Remove more of the pccard infrasturcture. CardBus Yenta driver (cbb)
still references the remaining bits. It needs some additiona work to
remove 16-bit support still, so it remains.
Sponsored by: Netflix
and remove non-present symbols that are now reported by kmod_syms.awk.
Reviewed by: emaste
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D32878