media: vsp1: Remove unused vsp1_subdev_internal_ops declaration

vsp1_subdev_internal_ops has been removed since commit 0efdf0f5
("[media] v4l: vsp1: Implement and use the subdev pad::init_cfg
configuration"), so remove it.

Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>