irqchip: gic-v3: Initial support for GICv3

The Generic Interrupt Controller (version 3) offers services that are
similar to GICv2, with a number of additional features:
- Affinity routing based on the CPU MPIDR (ARE)
- System register for the CPU interfaces (SRE)
- Support for more that 8 CPUs
- Locality-specific Peripheral Interrupts (LPIs)
- Interrupt Translation Services (ITS)

This patch adds preliminary support for GICv3 with ARE and SRE,
non-secure mode only. It relies on higher exception levels to grant ARE
and SRE access.

Support for LPI and ITS will be added at a later time.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Reviewed-by: Zi Shen Lim <zlim@broadcom.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Tirumalesh Chalamarla <tchalamarla@cavium.com>
Reviewed-by: Yun Wu <wuyun.wu@huawei.com>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Tested-by: Tirumalesh <Chalamarla&lt;tchalamarla@cavium.com>
Tested-by: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
Acked-by: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lkml.kernel.org/r/1404140510-5382-3-git-send-email-marc.zyngier@arm.com


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