lua: remove LUA_INSTALLED_FILES

Useless since the uninstall commands were removed in eb7bd9ef

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>