vhost: fix header copy to discontiguous desc buffer
vhost: fix header copy to discontiguous desc buffer

In the loop to copy virtio-net header to the descriptor buffer,
destination pointer was incremented instead of the source
pointer.

Fixes: fb3815cc614d ("vhost: handle virtually non-contiguous buffers in Rx-mrg")
Fixes: 6727f5a739b6 ("vhost: handle virtually non-contiguous buffers in Rx")
Cc: stable@dpdk.org

Signed-off-by: Maxime Coquelin <9a2667dee3b90866bbc9c2696cff2b7d5616c95a@redhat.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk