drm/sun4i: Fix DE2 VI layer format support

commit 20896ef1 upstream.

DE2 VI layer doesn't support blending which means alpha channel is
ignored. Replace all formats with alpha with "don't care" (X) channel.

Fixes: 7480ba4d ("drm/sun4i: Add support for DE2 VI planes")
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20200224173901.174016-4-jernej.skrabec@siol.net


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>