iio: orientation: hid-sensor-rotation: use ext_scan_type

iio: orientation: hid-sensor-rotation: use ext_scan_type

Make use of ext_scan_type to handle the dynamic realbits size of the
quaternion data. This lets us implement it using static data rather than
having to duplicate the channel info for each driver instance.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>