ARM: dts: add i2c device nodes for Exynos5420

This adds device-tree nodes for the i2c busses on Exynos
5420 platforms.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Signed-off-by: Rahul Sharma <rahul.sharma@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>