ppc/pnv: Use address_space_stq_be() when triggering an interrupt from PSI

Include the XIVE_TRIGGER_PQ bit in the trigger data which is how
hardware signals to the IC that the PQ bits of the interrupt source
have been checked.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20191007084102.29776-3-clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>