media: imx-jpeg: Set video drvdata before register video device

The video drvdata should be set before the video device is registered,
otherwise video_drvdata() may return NULL in the open() file ops, and led
to oops.

Fixes: 2db16c6e ("media: imx-jpeg: Add V4L2 driver for i.MX8 JPEG Encoder/Decoder")
Cc: <stable@vger.kernel.org>
Signed-off-by: Ming Qian <ming.qian@nxp.com>
Reviewed-by: TaoJiang <tao.jiang_2@nxp.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>