teflon/tests: Increase tolerance

On Rockchip, we need a tolerance of 8 to pass all tests (especifically
the whole MobileNetV1 model).

Though all other tests pass with a tolerance of just 2, 8 is still not
that high that we would risk letting bugs slip in.

Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29698>
1 file changed