sitnl: fix TUN/TAP confusion in error messages

sitnl: fix TUN/TAP confusion in error messages

The is_tun_p2p() function can return false for both TAP or TUN
interfaces (under certain conditions), therefore we should not
assume any TUN/TAP type when printing related messages.

Remove reference to TUN/TAP when printing messages under conditions
based on is_tun_p2p().

Signed-off-by: Antonio Quartulli <a@unstable.cc>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20200418013123.22551-1-a@unstable.cc>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg19775.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>