media: rockchip/vpu: Do not request id 0 for our video device

Pass -1 to video_register_device() to let the core assign the first
free id instead of trying to get id 0.
In practice it doesn't make a difference since video_register_device()
is not strict about id requests and will anyway pick the first free id
starting at the id passed in argument, and passing -1 has the same
effect as passing 0. But let's comply with the API doc and pass -1
here.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>