From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Tue, 24 Feb 2015 17:31:31 +0100

Recent iterator-related changes in vhost made it
harder to follow the logic fixing up the header.
In fact, the fixup always happens at the same
offset: sizeof(virtio_net_hdr): sometimes the
fixup iterator is updated by copy_to_iter,
sometimes-by iov_iter_advance.

Rearrange code to make this obvious.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Applied.