Revert "drm/exynos: fix plane-framebuffer linkage"

This reverts commit 4ad0514a81bdca95bf3b1bdbf3a78cf61ef9d914.
Going with the upstream fix instead.
drm/exynos: switch to universal plane API

The patch replaces legacy functions
drm_plane_init() / drm_crtc_init() with
drm_universal_plane_init() and drm_crtc_init_with_planes().
It allows to replace fake primary plane with the real one.
Additionally the patch leaves cleanup of crtcs to core,
this way planes and crtcs are cleaned in correct order.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>