media: atomisp: ov2680: Add dev local variable to probe()

Add a dev local variable to probe(), to allow shortening
&client->dev in various places, including further patches
in this series.

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