remove unmaintained TILE-Gx architecture

remove unmaintained TILE-Gx architecture

The TILE-Gx architecture and its driver mpipe are not maintained.
The code is removed to avoid confusion.

A last update has been done in 17.05 before removal.
It can be built with the updated toolchain:
	http://www.mellanox.com/repository/solutions/tile-scm/
and libgxio:
	http://www.mellanox.com/repository/solutions/tile-scm/libgxio-1.0.tar.xz

Quote from http://dpdk.org/ml/archives/dev/2017-February/057940.html
"
Mellanox agrees to remove TILE-Gx support from DPDK.org, but will continue
to support customers using DPDK.
Customer that needs support should contact Mellanox directly.
"

Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>