a function) which specifies how many lines will be skipped when scrolling
up when the bottom of the screen is reached. Dumb framebuffers skip 10
lines (as before) because the copies are s ... l ... o ... w, but it's
silly to skip 10 lines on VGA, since the copies are much faster, so we
only skip one in that case.
ioctl and mmap routines take a void *, rather than a struct device *,
so that they can be set up to work more easily when using a 'struct device *'
isn't appropriate. Add a cookie (void *) to be passed to the mmap and
ioctl routines. Rename a few struct members, and shuffle them into
a more sensible order.
