ARM: dts: add device tree support for exynos5 hdmi

This patch adds support for device tree based discovery for exynos5
hdmi. Hdmi node is also renamed with "exynos5-hdmi".

Signed-off-by: Rahul Sharma <rahul.sharma@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>