radv/gfx9: for fast clear use is_linear flag.
The legacy test won't work on gfx9. Reviewed-by:Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> Cc: "17.2" <mesa-stable@lists.freedesktop.org> Signed-off-by:
Dave Airlie <airlied@redhat.com> (cherry picked from commit 694d59fb)