drm: deprecate DRM_FORMAT_MOD_NONE

DRM_FORMAT_MOD_NONE is in the list of vendors, which is pretty
confusing. We already have DRM_FORMAT_MOD_VENDOR_NONE. Move it down in
the list of format modifiers.

DRM_FORMAT_MOD_NONE is an alias for DRM_FORMAT_MOD_LINEAR, however the
name is confusing: NONE doesn't mean that the modifier is implicit,
instead it means that the layout is linear. Deprecate it.

Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/a2j8KTgc26k5QniSAhDSTgCw4XWZhmsNHwG8UVa6U@cp4-web-014.plabs.ch