Ceph

We have currently two versions of DPDK in the source tree:

One under:
[submodule "src/dpdk"]
url = https://github.com/ceph/dpdk

And one as part of SPDK:
[submodule "src/spdk"]
url = https://github.com/ceph/spdk.git

Both submodules have different release/commit states:

src/dpdk: 2016-12-23

src/spdk/dpdk: 2017-11-17

If there is no specific reason for different versions we could simply remove src/dpdk and use the dpdk under src/spdk/dpdk

Any opinions on this?