hyperv: allow passing arbitrary data to sint ack callback

hyperv: allow passing arbitrary data to sint ack callback

Make sint ack callback accept an opaque pointer, that is stored on
sint_route at creation time.

This allows for more convenient interaction with the callback.

Besides, nothing outside hyperv.c should need to know the layout of
HvSintRoute fields any more so its declaration can be removed from the
header.

Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
Message-Id: <20180921081836.29230-6-rkagan@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>