drm/exynos: decon: Add support for hardware windows no 4 and 5

Enable support for 2 more hardware windows. This require enabling a few
more clocks and set proper plane type for all windows. In the new
configuration primary plane uses hardware window no 3 and cursor uses
window no 5. The remaining hardware windows are used for overlays. This
gives us an overlay plane both below and above primary plane for both
Decon and DeconTV (which uses hardware window nr 0 for background).

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