drm/xe/configfs: Reintroduce struct xe_config_device

drm/xe/configfs: Reintroduce struct xe_config_device

This time it will hold just pure configuration parameters, without
any configfs related stuff. This will help us define defaults data
without wasting space for unneeded data.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20250731193339.179829-8-michal.wajdeczko@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>