media: i2c: imx219: Access height from active format in imx219_set_ctrl

Use the active format height instead of the mode height in
imx219_set_ctrl(). This prepares for dropping the mode field from the
imx219 structure.

The state is retrieved using v4l2_subdev_get_locked_active_state() as
the subdev active state and the control handler share the same lock.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>