ARM: dts: Set up power domains for exynos4

This patch adds device tree nodes for power domains available
on EXYNOS4 SoCs.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>