Drop unmaintained add-on lcd4linux

Drop unmaintained add-on lcd4linux

This package has not received any updates or attention within the last
three years. It's sole known upstream URL (https://ssl.bulix.org/projects/lcd4linux/)
returns a HTTP error 404 nowadays, and the author was unable to locate
any upstream source that appears to be still maintained today.

Given the status quo, bugs in lcd4linux cannot be reported properly,
security issues won't be addressed (by anybody else then ourselves), and
technical questions cannot be clarified aside a reverse engineering
approach.

We should not allow such an add-on to be installed on a firewall system.

Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
Reviewed-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>