drm/exynos/vidi: convert to struct drm_edid

Prefer the struct drm_edid based functions for storing the EDID and
updating the connector.

It would be better if the vidi connection ioctl passed in the EDID size
separately instead of relying on the extension count specified in the
EDID, but that's what we have to rely on.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>