MIPS: PCI: remember nasid changed by set interrupt affinity

When changing interrupt affinity remember the possible changed nasid,
otherwise an interrupt deactivate/activate sequence will incorrectly
setup interrupt.

Fixes: e6308b6d ("MIPS: SGI-IP27: abstract chipset irq from bridge")
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org