drm/xe: Nuke xe from xe_devcoredump

xe is never set in xe_devcoredump but if xe_device is needed
devcoredump_to_xe_device() can be used.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Maarten Lankhorst <dev@lankhorst.se>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240123204454.246788-3-jose.souza@intel.com