ARM: EXYNOS: Add secure firmware support for l2x0 init

Based on a patch by Gu1 <gu1@aeroxteam.fr>
ARM: dts: Add arm-pmu node for exynos4412

The Exynos4412 has 4 cpus and each has a performance counter.
Thus, we should define 4 interrupts which are combined by irq-combiner for arm
pmu.

Signed-off-by: Chanho Park <chanho61.park@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>