media: cros-ec-cec: Support multiple ports in write command

Add a v1 of the CEC write command which contains a port parameter. Check
which versions of the write command the EC supports and use the highest
supported version. If it only supports v0, check that there is only one
port. With v0, the EC will assume all write commands are for port 0.

Signed-off-by: Reka Norman <rekanorman@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>