irqchip: GICv3: ITS: device allocation and configuration

The ITS has a notion of "device" that can write to it in order to
generate an interrupt.

Conversly, the driver maintains a per-ITS list of devices, together
with their configuration information, and uses this to configure
the HW.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1416839720-18400-9-git-send-email-marc.zyngier@arm.com


Signed-off-by: Jason Cooper <jason@lakedaemon.net>
Git-commit: 84a6a2e7fc18dae444c5c88cc6af8878552867a5
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


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