media: atomisp: ov2680: Drop v4l2_find_nearest_size() call from set_fmt()

Since we now calculate timings baded on the desired width and height,
any width and height are valid as long as they don't exceed the sensor's
dimensions.

Drop the v4l2_find_nearest_size() call and instead clamp the requested
width and height.

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