drm/xe: Move declarations under conditional branch

drm/xe: Move declarations under conditional branch

The xe_device_shutdown() function was needing a few declarations
that were only required under a specific condition. This change
moves those declarations to be within that conditional branch
to avoid unnecessary declarations.

Reviewed-by: Nitin Gote <nitin.r.gote@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20251007100208.1407021-1-tejas.upadhyay@intel.com
Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
(cherry picked from commit 15b3036045188f4da4ca62b2ed01b0f160252e9b)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>