requested by uwe@. These were wrong because they were receiving an
emulcookie yet they were accessops (thus having to receive an accesscookie).
Instead, just handle the WSDISPLAYIO_{GET,PUT}WSCHAR ioctls from the
driver's ioctl accessop.
As this reduces the amount of code needed to handle these operations to
two small functions in each driver, remove the WSDISPLAY_CHARFUNCS kernel
option.
Reviewed by, at least, uwe@ and macallan@. No objections in tech-kern@.