irqchip: atmel-aic: Add atmel AIC/AIC5 drivers

Add AIC (Advanced Interrupt Controller) and AIC5 (AIC5 is an evolution of
the AIC block) drivers.
Put common code in irq-atmel-aic-common.c/.h so that both driver can access
shared functions (this will ease maintenance).

These drivers are only compatible with dt enabled board and replace the
old implementation found in arch/arm/mach-at91/irq.c.

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Link: https://lkml.kernel.org/r/1405012462-766-4-git-send-email-boris.brezillon@free-electrons.com


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