[media] v4l2: put VIDIOC_DBG_G_CHIP_NAME under ADV_DEBUG

Only enable this ioctl if the VIDEO_ADV_DEBUG config option is set. This
prevents abuse from both userspace and kernelspace (some bridge drivers
abuse DBG_G_CHIP_IDENT, lets prevent that from happening again with this
ioctl).

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>