ARM: SAMSUNG: Add API to set platform data for s5p-tv driver

Commit 350f2f4d ("[media] v4l: s5p-tv: hdmi: add support for
platform data") makes the presence of platform data mandatory for
s5p-tv driver. Adding an API to plat-samsung for this purpose.

Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>