ARM: EXYNOS4: convert MCT to percpu interrupt API

MCT recently gained per cpu interrupts, and missed the fact that
ARM has moved to a genirq based implementation.

This patch converts the driver to the new API.

Boot tested on Origen.

Cc: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>