ARM: EXYNOS: Enable PMUs for exynos4

This patch defines irq numbers of ARM performance monitoring unit for exynos4.
Firs of all, we need to fix IRQ_PMU correctly and to split pmu initialization
of exynos from plat-samsung for easily defining it.

The number of CPU cores and PMU irq numbers are vary according to soc types.
So, we need to identify each soc type using soc_is_xxx function and to define
the pmu irqs dynamically. For example, the exynos4412 has 4 cpu cores and pmus.

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