drm/vkms: drop full alpha blending TODO

Now that VKMS supports full alpha blending on all planes, drop the
"ARGB format on primary plane" and "Full alpha blending on all planes"
tasks from the TODO list.
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Reviewed-by: Melissa Wen <mwen@igalia.com>
Reviewed-by: Arthur Grillo <arthurgrillo@riseup.net>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20230420232228.273340-2-mcanal@igalia.com

Documentation/gpu/vkms.rst

@@ -118,13 +118,8 @@ Add Plane Features
 
 There's lots of plane features we could add support for:
 
-- ARGB format on primary plane: blend the primary plane into background with
-  translucent alpha.
-
 - Add background color KMS property[Good to get started].
 
-- Full alpha blending on all planes.
-
 - Rotation, scaling.
 
 - Additional buffer formats, especially YUV formats for video like NV12.