pipe-loader: remove config from pipe_loader_create_screen

pipe-loader: remove config from pipe_loader_create_screen

The config passed into the screen should be independent from the state
tracker, because at least in the case of radeonsi, the screen structure
can be shared between different state trackers.

Incidentally, this also fixes crashes that were recently introduced.

Fixes: a35a9e7c ("gallium: add driconf options to pipe_screen_config")
Tested-by: Dieter Nützel <Dieter@nuetzel-hh.de>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>