Since FreedomBox does not allow any users but those belonging to 'admin' group
to login, using passwd driver for auth means that only admin can login to
postfix/dovecot. Fix this by reverting to using LDAP driver.
Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>