core/legal-info: don't generate big file with all license texts

core/legal-info: don't generate big file with all license texts

By aggregating all the license files into a single big text-only file
means we have no way to use license files that are binary blobs (e.g.
pdf, rtf...).

Just do not generate that big file; if the user still wants it, it is
very easy to create it afterwards.

Reported-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Luca Ceresoli <luca@lucaceresoli.net>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>