qapi: Define new QMP message for pvrdma

qapi: Define new QMP message for pvrdma

pvrdma requires that the same GID attached to it will be attached to the
backend device in the host.

A new QMP messages is defined so pvrdma device can broadcast any change
made to its GID table. This event is captured by libvirt which in  turn
will update the GID table in the backend device.

Signed-off-by: Yuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>