media: s3c-camif: Avoid inappropriate kfree()

s3c_camif_register_video_node() works with video_device structure stored
as a field of camif_vp, so it should not be kfreed.
But there is video_device_release() on error path that do it.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: babde1c2

 ("[media] V4L: Add driver for S3C24XX/S3C64XX SoC series camera interface")
Signed-off-by: Katya Orlova <e.orlova@ispras.ru>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>