busdma: kill filter functionality internally
Address filter functions are unused, unsupported, and now rejected.
Simplify some busdma code by removing filter functionality completely.
Note that the chains of parent tags become useless, and will be cleaned
up in the next commit.
No functional change intended.
Reviewed by: jhb
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D42894