drm/exynos: remove unused fields from struct exynos_drm_plane

Now after the move to use drm_plane_state directly struct drm_plane_state
has many unused fields, along with others that weren't used before the
plane state change. Thus remove them all.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

diff --cc drivers/gpu/drm/exynos/exynos_drm_drv.h
Simple merge