virtio-msg: EVENT_{AVAIL.USED} delete "all virtqueues" provision

This is hard to describe and real implementations may just use a loop
anyway.  So delete this for now anyway.

A loop is required in the bus when:
* One OoB notification can trigger multiple virtio devices
* One OoB notification can trigger SOME virtqueues but not all

So this value only covers one use case and it may cause more confusion
than value.

Signed-off-by: Bill Mills <bill.mills@linaro.org>

Author: wmamills

transport-msg.tex

@@ -1053,11 +1053,6 @@ \subsubsection{Overview}
 \hline
 \end{tabular}
 
-If virtqueue index is 0xFFFFFFFF then it indicates that all virtqueues should be
-polled for available buffers. This may be useful on the device side when the
-bus implementation is using out-of-band notifications, using polling, or when
-emulating or bridging to another virtio transport.
-
 The \textbf{Next wrap} field is the MSB of the 32 bit value. The
 \textbf{Next offset} field is the other 31 bits. These fields should be 0 if
 the VIRTIO_F_NOTIFICATION_DATA feature has not been negotiated. If the bus
@@ -1076,11 +1071,6 @@ \subsubsection{Overview}
 \hline
 \end{tabular}
 
-If virtqueue index is 0xFFFFFFFF then it indicates that all virtqueues should be
-polled for used buffers. This may be useful when the bus implementation is
-using out-of-band notifications, using polling, or when emulating or bridging
-to another virtio transport.
-
 \subsection{Bus Messages}\label{sec:Virtio Transport Options / Virtio Over Messages / Bus Messages}
 
 The bus messages defined in this specification facilitate device discovery,