spapr/irq: Drop spapr_irq_msi_reset()

spapr/irq: Drop spapr_irq_msi_reset()

PHBs already take care of clearing the MSIs from the bitmap during reset
or unplug. No need to do this globally from the machine code. Rather add
an assert to ensure that PHBs have acted as expected.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <156415228966.1064338.190189424190233355.stgit@bahia.lan>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
[dwg: Fix crash in qtest case where spapr->irq_map can be NULL at the
 new assert()]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>