package/clamav: Fix LICENSE_FILES after last version bump

Fixes
http://autobuild.buildroot.net/results/3a1/3a12aea6a7a3500883a6d0184da3bd8cebf50e7b/


and many others

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>