vsock: use new wait API for vsock_stream_sendmsg()

vsock: use new wait API for vsock_stream_sendmsg()

As reported by Michal, vsock_stream_sendmsg() could still
sleep at vsock_stream_has_space() after prepare_to_wait():

  vsock_stream_has_space
    vmci_transport_stream_has_space
      vmci_qpair_produce_free_space
        qp_lock
          qp_acquire_queue_mutex
            mutex_lock

Just switch to the new wait API like we did for commit
d9dc8b0f8b4e ("net: fix sleeping for sk_wait_event()").

Reported-by: Michal Kubecek <[email protected]>
Cc: Stefan Hajnoczi <[email protected]>
Cc: Jorgen Hansen <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Claudio Imbrenda <[email protected]>
Signed-off-by: Cong Wang <[email protected]>
Reviewed-by: Stefan Hajnoczi <[email protected]>
Signed-off-by: David S. Miller <[email protected]>