doc: announce ivshmem support removal

doc: announce ivshmem support removal

There was a prior call with an explanation of what needs to be done:
	http://dpdk.org/ml/archives/dev/2016-June/040844.html
- Qemu patch upstreamed
- IVSHMEM PCI device managed by a PCI driver
- No DPDK objects (ring/mempool) allocated by EAL

As nobody seems interested, it is time to remove this code which
makes EAL improvements harder.

Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
Acked-by: David Marchand <david.marchand@6wind.com>
Acked-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Acked-by: Jan Viktorin <viktorin@rehivetech.com>
Acked-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>