drm/exynos: enable support for exynos5420 hdmi device

Enable support for hdmi for exynos5420 hdmiphy. Add
compatible string in the of_match table. Also added
hdmiphy configuration values for exynos5420.

Signed-off-by: Rahul Sharma <Rahul.Sharma@samsung.com>
Signed-off-by: Shirish S <s.shirish@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>