drm/sun4i: Fix DE2 VI layer format support

commit 20896ef137340e9426cf322606f764452f5eb960 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>