Remove NetBSD compat shims for drivers originally shared with NetBSD/pc98.
NetBSD/pc98 was never merged into the main NetBSD tree and is no longer
developed. Adding locking to these drivers would have made the compat
shims hard to impossible to maintain, so remove the shims to ease
future changes.

These changes were verified by md5. Some additional shims can be removed
that do affect the compiled results that I will probably do in another
round.

Approved by: nyan (tentatively)