drm/xe: fix kernel-doc issues

drm/xe: fix kernel-doc issues

drivers/gpu/drm/xe/xe_guc_submit_types.h:47: warning: cannot understand
function prototype: 'struct guc_submit_parallel_scratch '

drivers/gpu/drm/xe/xe_devcoredump_types.h:38: warning: Function
parameter or member 'ct' not described in 'xe_devcoredump_snapshot'

CI doesn't appear to be running BAT anymore, assuming this is caused by
the CI.Hooks now failing due to above warnings.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>