drm/exynos: introduce exynos_drm_plane_config structure

This patch adds common structure for keeping plane configuration and
capabilities data. This patch is inspired by similar code developed by
Tobias Jakobi.

Changelog v2:
- fix vidi_win_types(i) call. vidi_win_types is not a function.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>