ARM: SAMSUNG: Fix HDMI related warnings

Silences the following warnings:
arch/arm/plat-samsung/devs.c:765:31: warning:
symbol 's5p_hdmi_def_platdata' was not declared. Should it be static?
arch/arm/plat-samsung/devs.c:767:13: warning:
symbol 's5p_hdmi_set_platdata' was not declared. Should it be static?

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