openvpn: move to meta-networking and tweak

* Move SRC_URI checksums next to SRC_URI
* Move packaging definitions to the end
* Set SUMMARY instead of DESCRIPTION
* Drop unused inc file

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>