irqchip: GICv3: ITS: irqchip implementation

The usual methods that are used to present an irqchip to the rest
of the kernel

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1416839720-18400-6-git-send-email-marc.zyngier@arm.com


Signed-off-by: Jason Cooper <jason@lakedaemon.net>
Git-commit: c48ed51c0d101ec4351530bdd6e1a01808f0a441
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Puja Gupta <pujag@codeaurora.org>