put iov_iter into msghdr

Note that the code _using_ ->msg_iter at that point will be very
unhappy with anything other than unshifted iovec-backed iov_iter.
We still need to convert users to proper primitives.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

net/vmw_vsock/vmci_transport.c

@@ -1850,7 +1850,8 @@ static ssize_t vmci_transport_stream_enqueue(
 	struct msghdr *msg,
 	size_t len)
 {
-	return vmci_qpair_enquev(vmci_trans(vsk)->qpair, msg->msg_iov, len, 0);
+	/* XXX: stripping const */
+	return vmci_qpair_enquev(vmci_trans(vsk)->qpair, (struct iovec *)msg->msg_iter.iov, len, 0);
 }
 
 static s64 vmci_transport_stream_has_data(struct vsock_sock *vsk)