media: atomisp: ov2680: Use devm_kzalloc() for sensor data struct

Use devm_kzalloc() to allocate the sensor data struct. It is always free-ed
as the last step of probe-error-exit or remove, so it can be devm-managed.

This will make unwinding things easier when support is added to the ov2680
code to use standard GPIO APIs instead of the custom atomisp_gmin code.

This also allows dropping the out_free label and use direct return
on errors.

This may seem like a functional change since the out_free label also
did a v4l2_device_unregister_subdev() but at the 2 changed returns
the device is not registered yet, so that always is a no-op and can
be dropped.

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>