media: atomisp: ov2680: s/dev/sensor/

Using dev as name for variables pointing to struct ov2680_device is a bit
unfortunate choice.

All the recently added / rewritten code is already using sensor for this,
replace the remaining usages of "struct ov2680_device *dev" with
"struct ov2680_device *sensor".

Note the power_up()/power_down() related functions are not changed as
these will be removed in one of the next patches.

No functional changes.

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>