openvpn: T3805: fix bool logic in verify_pki() for client mode
openvpn: T3805: fix bool logic in verify_pki() for client mode

Add support for OpenVPN client mode with only the CA certificate of the server
installed.

vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x