zbus: vded: msg_sub: Improve channel ref copy

The VDED was adding the channel information per clone. But it could be
done in the original buffer. This commit fixes that by adding the
channel information to the original buffer and not for each clone. As a
result, we have a more straightforward VDED execution with fewer copies.

Signed-off-by: Rodrigo Peixoto <rodrigopex@gmail.com>