media: vicodec: Add support for stateless decoder.

Implement a stateless decoder for the new node.

Signed-off-by: Dafna Hirschfeld <dafna3@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil-cisco@xs4all.nl: add 'return 0;' before default case in vicodec_try_ctrl()]
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>