media: atomisp: Remove the ACC device node

media: atomisp: Remove the ACC device node

The ACC /dev/video# device node uses a struct video_device embedded in
an atomisp_acc_pipe struct instead of in an atomisp_video_pipe struct.
Yet it uses the same file-ops and ioctl-ops even though it does not have
a videobuf queue, which makes e.g. the mmap fop nonsense.

Worse the only file-ops / ioctls which differentiate between
the 2 types and correctly do container_of on the right type
are the open/release fops and the vidioc_default handler.

The mmap and poll fops and *all* other ioctl handlers unconditionally
do container_of on the passed in struct video_device blindly assuming
they are dealing with the one embedded in the atomisp_video_pipe struct.

This makes it trivial for userspace to cause all sort of undefined behavior
by calling mmap, poll or the other ioctls on the ACC device node!

Presumably the use of the ACC device node was to allow making the special
ioctls to load custom programs while the other /dev/video# nodes were
already open, since the /dev/video# nodes can currently all be opened
only once (which needs to be fixed).

commit 4bbca788b6eb ("media: atomisp: remove private acceleration ioctls")
has removed the custom ATOMISP_ACC_* ioctls, so there no longer is any
reason to keep the ACC device node.

As explained above its presence can easily cause the kernel to crash,
so remove the ACC device node and the code for handling it.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>