dco: properly re-initialize dco_del_peer_reason

dco: properly re-initialize dco_del_peer_reason

After processing a message, all fields of the dco object should be
re-initialized so that future processings are not affected by stale
values.

This includes dco_del_peer_reason.

Since its values can start at 0, re-initialize it with -1.

Signed-off-by: Antonio Quartulli <a@unstable.cc>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <20230103202330.1835-1-a@unstable.cc>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg25881.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>