drm/sun4i: Add support for all HW supported DE2 RGB formats

Currently only a few RGB formats are supported by the DE2 driver. Add
support for all formats supported by the HW.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171201060550.10392-18-jernej.skrabec@siol.net