irqchip: armada-370-xp: Fix MSI interrupt handling

The MSI interrupts use the 16 high doorbells, which are notified by using IRQ1
of the main interrupt controller.

The MSI interrupts were handled correctly for Armada-XP and Armada-370 but not
for Armada-375 and Armada-38x, which use chained handler for the MPIC.

This commit fixes that by checking proper interrupt number in chained handler
for the MPIC.

Signed-off-by: Grzegorz Jaszczyk <jaz@semihalf.com>
Reviewed-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Fixes: bc69b8ad ("irqchip: armada-370-xp: Setup a chained handler for the MPIC")
Cc: <stable@vger.kernel.org> # v3.15+
Acked-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Link: https://lkml.kernel.org/r/1411643839-64925-2-git-send-email-jaz@semihalf.com


Signed-off-by: Jason Cooper <jason@lakedaemon.net>