drm/xe: Use ERR_CAST to return an error-valued pointer

Instead of directly casting and returning an error-valued pointer,
use ERR_CAST to make the error handling more explicit and improve
code clarity.

Signed-off-by: Yu Jiaoliang <yujiaoliang@vivo.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240906070109.1852860-1-yujiaoliang@vivo.com