irqchip/gic: Make sure all interrupts are deactivated at boot

When booting a GIC/GICv3 based system, we have no idea what
state the firmware (or previous kernel in the case of kexec)
has left the GIC, and some interrupts may still be active.

In order to garantee that we have a clean state, make sure
the active bits are cleared at init time.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Russell King <linux@arm.linux.org.uk>
Link: http://lkml.kernel.org/r/1447701208-18150-3-git-send-email-marc.zyngier@arm.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>