buildscript: patch source before generating feeds

.. otherwise the applied patches are not used while generating the
openwrt config.

Signed-off-by: Tim Niemeyer <tim@tn-x.org>
Reviewed-by: Tobias Klaus <tk+ff@meskal.net>

buildscript

@@ -135,6 +135,8 @@ prepare() {
     /bin/rm -rf "$target"
     cp -a src/openwrt "$target"
 
+    patch_target
+
     ## generate own feeds.conf
     #this local variable should be globally configure variable used in get_source and here
     local PACKAGEBASE=${PWD}/src/packages
@@ -166,8 +168,6 @@ prepare() {
         fi
     done
 
-    patch_target
-
     #saves ~200MB for each build
     test -d ./src/dl || mkdir ./src/dl
     ln -s ../../src/dl "$target"/dl