mesa: create multisample fallback textures like normal textures
This works if drivers upsample on upload (like all radeon ones do). The alternative is an unexpected GL error from anything calling _mesa_update_state and possibly other issues. Cc: 10.6 11.0 <mesa-stable@lists.freedesktop.org> Reviewed-by:Dave Airlie <airlied@redhat.com> (cherry picked from commit f432ae89)