drm/exynos: hdmi: use i2c_adapter instead of i2c_client

This patch changes i2c_client for ddc to i2c_adapter
because ddc needs only i2c_adapter.

Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>