connection: Fix broken log message when demarshalling short closure

Like the similar wl_log() message further into this function that was
fixed in commit 2fc248dc this should
be printing the sender_id saved earlier instead of *p.

Since p is incremented during the loop it would not only print an
incorrect object id, it could read past the end of the array.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>