drm/plane-helper: Warn if atomic drivers call non-atomic helpers

drm/plane-helper: Warn if atomic drivers call non-atomic helpers

The plane update and disable helpers are only useful for non-atomic
drivers. Print a warning if an atomic driver calls them.

Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220909105947.6487-4-tzimmermann@suse.de