irqchip: armada-370-xp: Allow using wakeup source

On the Armada 370/XP SoCs, in standby mode the SoC stay powered and it
is possible to wake-up from any interrupt sources. This patch adds
flag to the MPIC irqchip driver to let linux know this.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1427724278-12379-5-git-send-email-gregory.clement@free-electrons.com


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