drm/exynos: atomic phase 2: wire up state reset(), duplicate() and destroy()

Set CRTC, planes and connectors to use the default implementations from
the atomic helper library. The helpers will work to keep track of state
for each DRM object.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Joonyoung Shim <jy0922.shim@samsung.com>
Tested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Inki Dae <inki.dae@samsung.com>