Revert "scripts/download.pl: fix sourceforge url"

To use the new url, the project name would need to be appended multiple times,
let's hope the old redirect will continue to work in the future

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@30730 3c298f89-4303-0410-b956-a3cf2f4a3e73