The typdef and defines from dgaproc.h are used by drivers, so it needs to
remain part of the public API. But no need to clutter the public header
with non-exported function declarations.
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1323>