pipe_resource has a screen pointer, and some drivers expect to be able
to cast it to their specialized version.
This works fine until one of the debug driver is used, because in this
case the driver's pipe_screen subclass can't be obtained with a simple
cast.
To overcome this limitation, this commit introduce a new function with
a default implementation to get the real driver pipe_screen from the
generic interface.
Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30587>
c9806b3595