drm/xe/guc: Don't expose GuC privileged debugfs files if VF

Some of the GuC debugfs files require access to the data that is
not available on the VFs. Don't expose those files on the VF driver.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20250403142635.1821-3-michal.wajdeczko@intel.com