ppc/xive: tctx_notify should clear the precluded interrupt

ppc/xive: tctx_notify should clear the precluded interrupt

If CPPR is lowered to preclude the pending interrupt, NSR should be
cleared and the qemu_irq should be lowered. This avoids some cases
of supurious interrupts.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-14-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>