media: ipu6: Use the ISYS auxdev device as the V4L2 device's device

The V4L2 device has a struct device field used for a number of purposes,
one of which determining whether a created sub-device needs to increment
the module's use count to avoid unloading the module. Thus the owner field
in this case must refer to the ipu6-isys module, corresponding to the
auxdev of the IPU6 ISYS.

Fixes: f50c4ca0

 ("media: intel/ipu6: add the main input system driver")
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>