ARM: dts: Add hs-i2c nodes to exynos5420

Added high speed I2C nodes to Exynos5420 DT file.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>