media: atomisp-ov2680: Don't take the input_lock for try_fmt calls.

On ov2680_set_fmt() calls with format->which == V4L2_SUBDEV_FORMAT_TRY,
ov2680_set_fmt() does not talk to the sensor, so there is no need to
lock the dev->input_lock mutex in this case.

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>