media: v4l: async: refactor v4l2_async_create_ancillary_links

Return 0 without checking IS_ERR or PTR_ERR if CONFIG_MEDIA_CONTROLLER
is not enabled.

This makes cocci happier:

drivers/media/v4l2-core/v4l2-async.c:331:23-30: ERROR: PTR_ERR applied after initialization to constant on line 319

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>