[media] s5p-tv: hdmi needs I2C support

Building the s5p-tv HDMI support when CONFIG_I2C is disabled
gives us this build error:

s5p-tv/hdmi_drv.c: In function 'hdmi_probe':
s5p-tv/hdmi_drv.c:947:2: error: implicit declaration of function 'i2c_get_adapter' [-Werror=implicit-function-declaration]
  adapter = i2c_get_adapter(pdata->hdmiphy_bus);
  ^

This patch changes the Kconfig description to include I2C
as a dependency for this driver, so it cannot be configured
incorrectly.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>