[package] linux-atm: Update to stable version 2.5.1 from upstream project

   This commit integrates the upstream version of the linux-atm tools
   version 2.5.1.

   It simplify the patchset but keeps the debian-patches,
   prevent the usage of libflex on the target, and let the package
   compiles every tools.

   The Makefile only installs atmarp & atmarpd, but some useful debug
   programs are also included (like aread/awrite, atmdump,...) in the
   makefile, but commented by default.

Signed-off-by: Obinou <obconseil@gmail.com>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@20216 3c298f89-4303-0410-b956-a3cf2f4a3e73