drm/xe/uapi: silence kernel-doc errors

./include/uapi/drm/xe_drm.h:263: warning: Function parameter or member
'gts' not described in 'drm_xe_query_gts'

./include/uapi/drm/xe_drm.h:854: WARNING: Inline emphasis start-string
without end-string.

With the idea to also include the uapi file in the pre-merge CI hooks
when building the kernel-doc, so first make sure it's clean:

https://gitlab.freedesktop.org/drm/xe/ci/-/merge_requests/16



v2: (Francois)
  - It makes more sense to just fix the kernel-doc for 'gts'

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Francois Dugast <francois.dugast@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Francois Dugast <francois.dugast@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>