buildscript: remove unneeded global download directory link

Some time ago, the firmware created a directory for each target
and built OpenWrt separately there. In this situation, it made
sense to download files only once and share them between these
build directories.

However, since we nowadays only have one build directory for all
targets, this makes no sense anymore. Remove the link.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
Reviewed-by: Robert Langhammer <rlanghammer@web.de>

buildscript

@@ -142,10 +142,6 @@ prepare() {
     # exists in builddir.
     apply_variant
 
-    #saves ~200MB for each build
-    test -d ./src/dl || mkdir ./src/dl
-    ln -s ../src/dl "$builddir"/dl
-
     update_feeds
 }