vp9_mc_template: limit assert to SCALED == 0

The handling of the other block sizes was limited to 'SCALED == 0' in
commit dc96c0f9fc96bf4167633befc074394062793322, so this assert should
be disabled, too, as it can now be triggered.

Reviewed-by: Ronald S. Bultje <rsbultje@gmail.com>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
