drm/exynos: hdmi: remove the i2c drivers and use

The i2c client was previously being passed into the hdmi driver via a
dedicated i2c driver, and then a global variable. This patch removes all
of that and just uses the device tree to get the i2c_client. This patch
also properly references the client so we don't lose it before we're
done with it.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
[seanpaul changed to phandle lookup instead of using of node name]
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Inki Dae <inki.dae@samsung.com>