drm/exynos: Implement drm_connector directly in vidi driver

This patch implements drm_connector directly in the vidi
driver, this will allow us to move away from the exynos_drm_connector
layer.

Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Inki Dae <inki.dae@samsung.com>