examples/vhost: remove functions implemented in lib
examples/vhost: remove functions implemented in lib

Those functions are integrated into the user space vhost library:
virtio_dev_rx, virtio_dev_merge_rx, virtio_dev_tx, virtio_dev_merge_tx,
copy_from_mbuf_to_ring, gpa_to_vva.

Signed-off-by: Huawei Xie <3b3be4428106761300a2ee559c9f71ecdb091553@intel.com>
Acked-by: Changchun Ouyang <593bf1f161e79772915ea885e47cf0e95f4498c0@intel.com>

phermansson/dpdk,phermansson/dpdk,phermansson/dpdk,phermansson/dpdk