Revert "Merge branch 'vsock-virtio'"

This reverts commit 0d76d6e8 and merge
commit c402293b, reversing changes made
to c89359a4.

The virtio-vsock device specification is not finalized yet.  Michael
Tsirkin voiced concerned about merging this code when the hardware
interface (and possibly the userspace interface) could still change.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>