ARM: dts: change compatible strings for EXYNOS5250 hdmi subsystem

This patch renames the combatible strings for hdmi, mixer, ddc
and hdmiphy. It follows the convention of using compatible string
which represent the SoC in which the IP was added for the first
time.

Signed-off-by: Rahul Sharma <rahul.sharma@samsung.com>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>