media: davinci: vpif_display: Remove unused v4l2-async code

There are no users for vpif_display_config.asd_sizes
and vpif_display_config.asd members, which means the v4l2-async
subdevices aren't being defined anywhere.

Remove the v4l2-async, leaving only the synchronous setup.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Reviewed-by: Helen Koike <helen.koike@collabora.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>