fix backup script path

[distro-setup] / filesystem / etc / exim4 / conf.d / transport / 30_exim4-config_dovecot_lmtp

# not currently used, but
dovecot_lmtp:
        driver = lmtp
        socket = /var/run/dovecot/lmtp
        #maximum number of deliveries per batch, default 1
        batch_max = 200