media: atomisp-ov2680: Fix ov2680_set_fmt()

media: atomisp-ov2680: Fix ov2680_set_fmt()

On sets actually store the set (closest) format inside ov2680_device.dev,
so that it also properly gets returned by get_fmt.

This fixes the following problem:

1. App does an VIDIOC_SET_FMT 640x480, calling ov2680_set_fmt()
2. Internal buffers (atomisp_create_pipes_stream()) get allocated
   at 640x480 size by atomisp_set_fmt()
3. ov2680_get_fmt() gets called later on and returns 1600x1200
   since ov2680_device.dev was not updated. So things get configured
   to stream at 1600x1200, but the internal buffers created during
   atomisp_create_pipes_stream() do not get updated in size
4. streaming starts, internal buffers overflow and the entire
   machine freezes eventually due to memory being corrupted

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