[media] v4l: smiapp: Return V4L2_FIELD_NONE from pad-level get/set format

The SMIA++ sensors are progressive, always return the field order set to
V4L2_FIELD_NONE.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>