[media] s5p-jpeg: Eliminate double kfree()

video_unregister_device() calls device_unregister(), which calls
put_device(), which calls kobject_put(), and if this is the last reference
then kobject_release() is called, which calls kobject_cleanup(), which
calls ktype's release method which happens to be device_release() in this
case, which calls dev->release(), which happens to be
v4l2_device_release() in this case, which calls vdev->release(), which
happens to be video_device_release(). But video_device_release() is
called explicitly both in error recovery path of s5p_jpeg_probe() and
in s5p_jpeg_remove(). The pointers in question are not nullified between
the two calls, so this is harmful.

This patch fixes the driver so that video_device_release() is not called
twice for the same object.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>