irqchip: st: Supply new driver for STi based devices

This driver is used to enable System Configuration Register controlled
External, CTI (Core Sight), PMU (Performance Management), and PL310 L2
Cache IRQs prior to use.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lkml.kernel.org/r/1424272444-16230-3-git-send-email-lee.jones@linaro.org


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