ARM: dts: add CCI node for exynos5420

Add device-tree bindings for the ARM CCI-400 on Exynos5420. There
are two slave interfaces: one for the A15 cluster and one for the
A7 cluster.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Signed-off-by: Abhilash Kesavan <a.kesavan@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>