Break 'try 256 dco devices' loop on EPERM

Break 'try 256 dco devices' loop on EPERM

If we get a permission denied error on one DCO device, trying 255 more
times will not succeed, and just fill the log file with errors.

Also, remove the msg() call there because it was at debug level
(needed --verb 4 to be seen), didn't see the correct errno, and the
sitnl code already prints the error.

v2: use "else if"

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Antonio Quartulli <a@unstable.cc>
Message-Id: <20220804082502.1750074-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg24799.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>